We investigate whether the financial riskiness of large US audit firm clienteles varied with the changing audit litigation liability environment during the period 1975-1999. Partitioning the period of study into four distinct periods [a benchmark period (1975-1984), a period of increasing concerns about litigation liability (1985-1989), a period of lobbying for reform (1990-1994) and a post-relief period (1995-1999)], we find some evidence of risk decreases during 1985-1989, strong evidence of risk decreases during 1990-1994 and strong evidence of risk increases during 1995-1999. However, we also find that over the period of our study, a time during which Big Six market shares grew appreciably, the proportion of litigious-industry clients in Big Six client portfolios grew at about the same rate as the proportion of such clients in the population. Moreover, the Big Six share of the financially riskiest clients in the economy did not grow as fast as overall Big Six market share. In sum, while our evidence is consistent with the hypothesis that the riskiness of Big Six client portfolios responded to changes in the audit litigation liability environment, we find no systematic evidence of a race to the bottom or bottom fishing by these firms in a bid to increase their market shares.