PurposeThe purpose of this paper is to empirically test a new theory called the balanced theory of port competitiveness.Design/methodology/approachData were collected from multiple respondents in 72 of the largest container ports. The instrument was translated into English, Simplified Chinese, Korean, and French. The data were collected through online and paper-based surveys. The data were analyzed using analytical hierarchy process.FindingsThe theory was shown to explain the behavior of port stakeholders in improving competitiveness by balancing the need to attract new customers with that of attracting new investors when making decisions, which can often be contradictory. The analysis showed significant effects for the five variables of volume competitiveness (VC) and the five variables of investment competitiveness.Research limitations/implicationsThis study is limited in that it only tested the balanced theory on the largest container ports. The decisions by port managers may differ at smaller ports or those that do not handle containers.Practical implicationsPort stakeholders now have a ten-variable model of the factors needed to attract new customers and investors. These variables, and their tradeoffs, can evaluate the impact of managerial decisions on port competitiveness.Originality/valueThis study informs the literature by being the first to test a new theory that explains a greater level of port stakeholder behavior when improving competitiveness. Prior to this study, VC and investor competitiveness had only been studied separately, although they were related in practice.