Generalized Supremum Augmented Dickey-Fuller Research Articles

Quantitative Modeling of Financial Contagion: Unraveling Market Dynamics and Bubble Detection Mechanisms

This study explored the complex interplay and potential risk of financial contagion across major financial indices, focusing on the Bucharest Exchange Trading Investment Funds Index (BET-FI), along with global indices like the S&P 500, Nasdaq Composite (IXIC), and Dow Jones Industrial Average (DJIA). Our analysis covered an extensive period from 2012 to 2023, with a particular emphasis on Romania’s financial market. We employed Autoregressive Distributed Lag (ARDL) modeling to examine the interrelations among these indices, treating the BET-FI index as our primary variable. Our research also integrated Exponential Curve Fitting (EXCF) and Generalized Supremum Augmented Dickey–Fuller (GSADF) models to identify and scrutinize potential price bubbles in these indices. We analyzed moments of high volatility and deviations from typical market trends, influenced by diverse factors like government policies, presidential elections, tech sector performance, the COVID-19 pandemic, and geopolitical tensions, specifically the Russia–Ukraine conflict. The ARDL model revealed a stable long-term relationship among the variables, indicating their interconnectedness. Our study also highlights the significance of short-term market shifts leading to long-term equilibrium, as shown in the Error Correction Model (ECM). This suggests the existence of contagion effects, where small, short-term incidents can trigger long-term, domino-like impacts on the financial markets. Furthermore, our variance decomposition examined the evolving contributions of different factors over time, shedding light on their changing interactions and impact. The Cholesky factors demonstrated the interdependence between indices, essential for understanding financial contagion effects. Our research thus uncovered the nuanced dynamics of financial contagion, offering insights into market variations, the effectiveness of our models, and strategies for detecting financial bubbles. This study contributes valuable knowledge to the academic field and offers practical insights for investors in turbulent financial environments.

The study on the effect of restrictive rosewood trade policies on China’s rosewood import prices

PurposeRosewood, as the most internationally traded endangered species, is subject to a series of restrictive trade policies globally. China has historically been the largest importer of rosewood in the world. The fluctuation of China’s rosewood import prices will have a profound impact on the global rosewood trade pattern. This study, therefore, assessed the impact of restrictive trade policies on China’s rosewood import prices to explore the fluctuation rule of rosewood trade prices under restrictive policies.Design/methodology/approachThe study built a partial equilibrium framework about the formation mechanism of rosewood import price bubbles under supply constraints. On this basis, with China’s daily import prices of major rosewood species, the generalized supremum augmented Dickey–Fuller (GSADF) and backward supremum augmented Dickey–Fuller (BSADF) tests were applied to explore the effect of restrictive trade policies on China’s rosewood import prices.FindingsThe empirical analysis revealed that there were multiple price bubbles for five of the seven rosewood species. The largest bubbles were always created before and after the deployment of supply constraints. The empirical results for the counterfactual examples implied that price bubbles would not have occurred if restrictive rosewood trade policies had not been implemented. The above findings indicated that these measures tended to trigger significant price bubbles in China’s rosewood imports.Originality/valueThe effect of restrictive rosewood trade policies on rosewood trade prices had not yet been explored in previous research studies. This study empirically analyzed the effect of restrictive trade policies on China’s rosewood import prices using econometric models.

The quest for explosive bubbles in the Indonesian Rupiah/US exchange rate: Does the uncertainty trinity matter?

The Generalized Supremum Augmented Dickey-Fuller (GSADF) technique is performed to resolve whether the Indonesian Rupiah/US exchange rate has experienced multiple explosive bubbles. The GSADF uncovers that the Indonesian Rupiah/US exchange rate deviates from the fundamental values by six times from January 1985 to September 2023, periodically indicating the presence of numerous explosive behaviors. Once the full-sample period separates into the managed-floating regime and the free-floating regime, the GSADF still detects multiple bubbles. Of particular curiosity on uncertainty trinity, this study underlines that global geopolitical risk negatively drives explosive actions in the ratio of exchange rates for non-traded and traded goods. The global economic policy uncertainty negatively affects speculative bubbles in the exchange rate and the ratio of exchange rates for non-traded. The country's geopolitical risks negatively strike only speculative bubbles in the exchange rate. Further, we find heterogeneity in our results by examining different exchange rate systems. The robustness checks further firmly ascertain across baseline empirical findings.

Chinese eSports Industry’s Boom and Recession: Evidence From Bubble Detection Framework

This paper aims to explore whether the development of competitive computer gaming (eSports) industries is sustained in China. In doing so, we apply the Generalized Supremum Augmented Dickey-Fuller (GSADF) method to investigate when the bubbles originated and crashed in the Chinese eSports market from 2014 to 2021. Utilizing the data of the Chinese Electronic Sports Thematic Index (CESI), the empirical outcomes show that the Chinese eSports industry may deviate from its market value and that the industry witnesses bubble behaviors. The latent reasons might be attributed to government policies, economic growth, stock market crises, and venture capital investments. Therefore, to promote the stabilized and sustained development of the eSports industry in China, regulators and authorities should pay attention to the evolution of bubbles. Moreover, maintaining policy consistency and continuity may be beneficial in stabilizing investors’ expectations and reducing speculative investment behaviors. JEL Classification: G10, Z23, Z28.

Identifying price bubbles in copper market: Evidence from a GSADF test approach.

This paper uses the test proposed by Generalized Supremum Augmented Dickey-Fuller to identify whether there are multiple bubbles in copper price. The empirical results show that base on market fundamentals, there are seven bubbles existed from January 1980 to March 2023. Through analyses, the first two bubbles can be explained by the demand from Japan by the industry concentration and persistent supply constraint. The third to sixth bubbles are mainly negatively impacted by the global financial crisis and growing demand of China. The last bubble is caused by the economic recovery from Covid-19. The logit regression has stated that aluminum price, copper production, all metals index and GDP have a positive impact on copper bubbles, while China's copper imports and precious metals price negatively explains copper bubbles. The main contributions are the investigation of the copper price bubbles, its determinants and the different technique of GSADF to detect copper price bubbles. Furthermore, it provides helpful information for those investors to make reasonable investment decisions and thus, avoid potential price risk.

Based on GSADF model - To study the impact of surging cross-border capital flows and their internal structure on economic growth

This paper measures surges using the Generalized Supremum Augmented Dickey-Fuller (GSADF) model based on capital flows data for 64 economies from 2003:Q1 to 2020:Q4. Then, this paper examines the impact of surges and the internal structure (abnormal liability flows and abnormal asset flows) on economic growth in the recipient economy, and further investigate the heterogeneity among economies with different levels of economic development. This paper finds that surges can positively contribute to economic growth in the recipient economy. In terms of the internal structure of surges, overall, abnormal liability flows have a significant positive effect on economic growth, while abnormal asset flows have no significant effect. Emerging economies perform in line with the overall, while economic growth in developed economies is positively boosted by both abnormal liability flows and abnormal asset flows together. Our research has important reference value for China to prevent risks of surges and their inherent structural changes.

ARE THERE DIGITAL TECH BUBBLES IN CHINA?

This exploration employs the generalized supremum augmented Dickey-Fuller (GSADF) approach to explore whether there are digital tech bubbles in China. The empirical results suggest the existence of multiple digital tech bubbles, which are mostly accompanied by an excessive rise. However, the appearance of digital tech bubbles is curbed since 2016, mainly due to the increasing mature regulations in relevant fields. Besides, bubbles in different digital technologies are similar during the same period, which could be attributed to the close relationships among them. Additionally, we further investigate the factors influencing the explosive behaviours, and find that the Chinese stock market positively affects digital tech bubbles, while economic policy uncertainties and situations negatively influence such explosive behaviors. In the context of the new round of scientific and technological revolution and industrial transformation, these conclusions provide valuable implications to achieve the target of constructing a “Digital China” by becoming moderately cautious about potential bubbles in the digital tech industry.

Exploring Bubbles in the Digital Economy: The Case of China

This study identifies the cyclical boom-and-bust episodes in digital economy-related assets and determines whether bubbles exist in China's digital economy. The extant literature mainly focuses on tech or cryptocurrency bubbles and has not considered the digital economy. Therefore, we use data from March 22, 2017, to March 3, 2022, and employ the generalized supremum augmented Dickey–Fuller (GSADF) technique to capture the irrational prosperity in China's digital economy. The conclusion suggests the existence of five bubbles in China's digital economy, all accompanied by extreme fluctuations in related asset prices, which the asset-pricing model supports. Under the backdrop of the scientific and technological revolution and industrial transformation, this exploration offers meaningful suggestions for China to facilitate the sound development of the digital economy.

Are there bubbles in shipping freight during COVID-19?

This study examines the potential bubbles' shipping freight rates during the pandemic through the Generalized Supremum Augmented Dickey-Fuller test. The results explore multiple bubbles in the freight rates during corona disease (COVID-19). Moreover, the result finds that Baltic Dry Index is the most explosive and shows four bubbles, followed by Baltic Clean Tanker Index. The volatile behavior has been more frequent and pronounced since the second quarter of 2021, mainly instigated by the economic recovery. The results detect four bubbles in Baltic Dry Index caused by strong demand for raw materials and uncertainty restrictions. Furthermore, a single bubble in the Baltic Dirty Tanker Index is caused by the increasing oil price, growing demand for floating storage while burst due to new restrictions of the second wave, declining oil prices, and shortages of vessels. The need for oil products, logistical problems and the highest oil prices are the leading determinants of Baltic Clean Tanker index bubbles.

Bubble behaviors in lithium price and the contagion effect: An industry chain perspective

Ensuring the smooth operation of lithium market is crucial for the transition to cleaner sources of energy. From the perspective of boom-bust cycles in the Chinese lithium market, this study explores the existence of periodically bubble behaviors in lithium price utilizing the Generalized Supremum Augmented Dickey-Fuller method. The method delivers an innovative consistent date-stamping assessment for the exuberance and collapse of bubble episodes. We further investigate the interdependence and contagion effects of bubble behaviors in lithium industry chain. The results reveal that multiple bubbles in the Chinese lithium market are confirmed, which are basically accompanied by excess market fluctuations. The finding is consistent with the asset pricing model which implies both expected and invisible components exist in asset prices. The bubble contagion effect from lithium upstream to midstream is demonstrated, while the interdependence effect and bilateral contagion effect are confirmed within the same production stage in lithium industry chain. The findings provide important supporting basis for policymakers to gain a better insight into the dynamics of explosive behaviors in lithium industry chain and to construct preventive policies to maintain stable development of lithium market.

Bubble behaviors in nickel price: What roles do geopolitical risk and speculation play?

The stable operation of nickel market provides essential safeguard for the realization of global sustainable energy transition. In the context of prominent geopolitical risks and financial market instability, the explosive dynamics of nickel market price have not been thoroughly investigated. From a boom-bust cycle perspective, this study examines the existence of periodically bubble behaviors in nickel price utilizing the Generalized Supremum Augmented Dickey-Fuller method. The method delivers an innovative consistent date-stamping assessment for the exuberance and collapse of bubble episodes. This paper further probes into the effects of geopolitical risk, speculations, demand, supply and dollar on bubbles through logistic technique. The results find that four boom-bust cycles in nickel price are detected during 1990–2022, which are basically accompanied by extreme market volatility. This finding is in line with the asset pricing model which implies both expected and invisible components exist in asset price. In terms of macroeconomic determinants, nickel demand positively affects the boom-bust behaviors, while nickel supply and dollar dynamics have a negative impact on bubble occurrence. Particularly, geopolitical risk and speculations are proven to be important drivers in boosting the explosiveness of bubbles. To counter the hazardous economic consequences of bubble collapse, policymakers should formulate precautionary policies in the face of complicated geopolitical landscape and volatile capital market environment.

Testing for Multiple Bubbles in the Nigerian Stock Exchange

Monthly All Share Index data from 1985M01-2021M12 was sourced from the Central Bank of Nigeria and the Central Securities Clearing System of the Nigerian Stock Exchange; to analyze multiple bubble periods. The supremum Augmented Dickey Fuller (SADF) and Generalized supremum Augmented Dickey Fuller (GSADF) quantitative model with 1000 repetitions along with a window size of 42 was selected to carry out the Monte Carlo simulation at the 95% confidence level. From the Backward SADF estimation, three periods of explosive pricing and collapses were detected. The study therefore recommends that market regulators should promote market information and support regular training of market participants to stem speculations and reduce arbitrage. Overall, well-informed risk management practices should be established to guard against market losses.

Which risks drive European natural gas bubbles? Novel evidence from geopolitics and climate

Ensuring the natural gas market's sound and ordered progress is crucial to Europe's sustainable development. This investigation employs the Generalized Supremum Augmented Dickey-Fuller (GSADF) approach to explore whether there are multiple bubbles in the European natural gas market. Also, we further investigate the influencing factors that contributed to these boom and bust episodes. The empirical results suggest that the multiple European natural gas bubbles are mostly accompanied by abnormal fluctuations, which is consistent with the asset pricing model. In addition, geopolitical and climate factors could increase the possibility of European natural gas bubbles, where the “cold winter” caused by the La Nina event brings more impetus to these bubbles than the “warm winter” due to the El Nino phenomenon, and Russia's geopolitical conflict with Ukraine is more likely to cause bubbles. Besides, the international oil market and European economic situation also exert positive effects on such explosive behaviours. Against the backdrop of an increasingly serious energy crisis in Europe, the above conclusions provide valuable implications to promote European sustainable development by reducing over-dependence on Russian energy and preventing dramatic surges in natural gas demand.

COVID-19 Pandemic and Speculative Behaviors: An Empirical Evidence of Stock Markets

The recent economic developments and outcomes have shown that the COVID-19 pandemic has been highly, but also negatively, correlated with financial markets and thus the financial system. This situation led to an increase in uncertainty and fragility in the economy. In this sense, this study aims to assess the speculative price behavior that occurred during the COVID-19 outbreak in the stock markets of 13 major countries. Daily data for the period between November 1, 2019 and October 23, 2020 are used to assess speculative price behavior. The empirical estimation strategy is based on the Supremum Augmented Dickey-Fuller (SADF) test and the Generalized Supremum Augmented Dickey-Fuller (GSADF) test. According to the estimation results, the SADF and GSADF test statistics show that the estimates are significant for the 13 specified stock market indexes. This empirical result shows that the COVID-19 pandemic has contagion effects on various types of financial markets, leading to bubble formation during the given sample period.

Is there evidence of mild explosive behavior in Alaska North Slope crude oil prices?

Alaska has long been important to U.S. oil production. With the sixth largest amount of proven reserves of any state and >95% of oil production occurring on the North Slope, Alaska will continue to be an important factor in U.S. energy production. Given the importance of the North Slope crude oil to West Coast refineries, it is surprising that very few studies have investigated the prevailing price of crude oil from the North Slope: the Alaska North Slope West Coast price (ANS). This study provides evidence of mildly explosive behavior in the time series of ANS price relative to the consumer price level, Alaska oil production, and a measure of oil stocks by utilizing the recursive generalized supremum Augmented Dickey-Fuller of Phillips, Shi, and Yu (2015). The sample period spans from May 1987 until September 2020 and we find evidence of mild explosive behavior prior to and during the 2007–2009 recession. Our findings are consistent with others who found mildly explosive behavior in other oil prices during the same period.

Oil price explosivity and stock return: Do sector and firm size matter?

The paper examines whether the oil price series contains price explosivity and if price explosivity exists whether it offers excess return for oil-related, oil-substitute, and oil-user companies in US stock markets. Moreover, we investigate whether the size effect moderates the relationship between oil price explosivity and stock returns. We use monthly West Texas Intermediate crude oil prices between January 1986 and December 2019 and employ the Generalized Supremum Augmented Dickey-Fuller test to detect the price explosivity. Feasible Generalized Least Squares estimator is also implemented to capture the impact of oil price bubble on stock returns of US companies. The results indicate multiple episodes of price explosivity which mostly coincides with the 2008 financial crisis. The price explosivity leads to an excess return for oil-related companies; whereas, it negatively impacts oil-substitute and oil-user firms. However, the effect of oil price explosivity on stock returns is heterogeneous across size groups. The results provide key insightful information to policymakers and investors. Policymakers should prevent the occurrence of price explosivity to increase the efficiency of an oil futures market. Given the diverse impact of oil price explosivity on the stock return across sectors and sub-size groups, investors can maximize their profits by rebalancing their portfolio based on oil dependency and the firm's size.

Policy-driven or market-driven? Evidence from steam coal price bubbles in China

This paper first verifies the existence and determinants of multiple bubbles in the steam coal market in China since the abolition of the double-track pricing system of coal and electricity in 2012. The Generalized Supremum Augmented Dickey-Fuller (GSADF) method confirms that the explosive bubbles originated mainly in 2013, 2014, 2015, 2016, and 2020, but this is not in accordance with the bubble model. The formation of bubbles is mainly due to policy changes related to de-capacity and environmental regulation. Furthermore, we find that price bubbles start in producing regions and transmit to the consumption regions. The demand-side factors drive the bubbles to spread in the reverse direction. The implication can infer that policy intervention in the coal industry should be reduced to ensure a market-oriented price mechanism and market stability. Producers and consumers, and investors need to pay attention to the spill over of price bubbles among regions, especially in major coal-producing areas.

Foreign Exchange Volatility and the Bubble Formation in Financial Markets: Evidence From The COVID-19 Pandemic

This paper applies recursive right-tailed unit root tests to detect bubble activity for Turkish Lira against financially most-traded five currencies (i.e., the US Dollar (USD/TRY), the British pound (GBP/TRY), the Euro (EUR/TRY), the Chinese Yuan (CNY/TRY) and the Russian Ruble (RUB/TRY)) over January 2, 2015 to February 12, 2021. It can be identified from the Supremum Augmented Dickey–Fuller (SADF) and the Generalized Supremum Augmented Dickey-Fuller (GSADF) tests statistics that there is a high degree of evidence of bubble activity which characterizes all five exchange rates both in the full-sample period and in the sub-periods, including the pre-COVID-19 era (January 2, 2015 to November 15, 2019) and the COVID-19 era (November 18, 2019 to February 12, 2021). The empirical results also indicate that positive bubbles are common for each selected exchange rate and the multiple bubbles were intensified during the COVID-19 period, referring that forex markets became relatively more inefficient compared to the pre-COVID-19 period.

Is there a price bubble in the exchange rates of the developing countries? The case of BRICS and Turkey

PurposeThe last decades have experienced increasingly integrated global political and economic dynamics ranging especially from the influence of exchange rates and trade amid other sources of uncertainties. The purpose of this study is to examine the exchange rate dynamics of Brazil, Russia, India, China, and South Africa (BRICS) and the Republic of Turkey.Design/methodology/approachGiven this perceived global dynamics, the current study examined the BRICS countries and the Republic of Turkey's exchange rate dynamics by using the United States (US) monthly dollar exchange rate data between January 2002 and August 2019. The price bubble which is expressed as exceeding the real value of assets' prices which is observably caused by speculative movements is investigated by using the Supremum Augmented Dickey-Fuller (SADF) and the Generalized Supremum Augmented Dickey-Fuller (GSADF) approaches.FindingsAccordingly, the GSADF test results opined that there are price bubbles in the dollar exchange rate of other countries except for the United States Dollar (USD)/Indian Rupee (INR) exchange rate. As the related countries are classified as developing countries in terms of their structure, they are also expectedly the subject of speculative exchange rate movements. Speculative movements in exchange rates may cause serious problems in national economies.Originality/valueThus, the current study provides a policy framework to the BRICS countries and the Republic of Turkey.

Bubble detection in Bitcoin and Ethereum and its relationship with volatility regimes

PurposeThe aim of this paper is to test the existence of bubbles for the daily prices of cryptocurrencies Bitcoin and Ethereum and verify if there is a relationship between bubbles and volatility regimes.Design/methodology/approachThe authors test the presence of bubbles with the generalized supremum augmented Dickey–Fuller (GSADF) test using critical values simulated by the bootstrap procedures of Gutierrez (2011), Harvey et al. (2016) and Pedersen and Schütte (2020). Also, the authors estimate Markov regime switching generalized autoregressive conditional heteroskedasticity model for these cryptocurrencies.FindingsThe GSADF test result indicates the presence of bubbles for both cryptocurrencies. Simulating critical values by wild-bootstrap, which is robust to non-stationary volatility, leads to the highest number of bubbles in both cryptocurrencies. In addition, based on the estimates of conditional variance models with regime changes, the authors find that the bubbles identified are associated with a regime of low returns volatility, indicating a change in the trade-off between risk and return when the prices of cryptocurrencies differ from their fundamental values.Originality/valueTo the best of the authors knowledge, there are no studies that test the explosive behavior for cryptocurrencies by the GSADF test using the bootstrap method to simulate critical values from the procedures of Harvey et al. (2016) or Pedersen and Schütte (2020). These bootstrapping procedures are robust to heteroscedasticity and avoid the detection of false bubbles. Further, the advantage of Harvey et al. (2016) procedure is the robustness to non-stationary volatility.