The US economy experienced major regulatory changes in the banking and finance industry with the passage of five major acts over the period 1980 to 1991. This has generated an extensive literature investigating the effects of these changes on the US banking industry. In particular, this body of research has examined the share market reaction to regulatory changes, as well as their impact on the risk, return, market value and profitability of banking industry stocks. Generally, it has been found that the regulatory changes have had a substantial impact, although the effect has not been uniform across all depository institutions. This paper extends this literature by analysing the stability of a sample of eighteen US banking industry stock betas across five periods: a pre-regulatory change period, a monetary experiment period, a deregulation period, a reregulation period and a post-regulatory change period. Based on an analysis of weekly returns, we find that the level of bank risk has increased. Further, we also find a tendency towards greater beta instability in both the monetary experiment and deregulation samples. The degree of beta instability is lowest in the pre-regulatory change and post-regulatory change samples. Overall the monetary experiment and regulatory change coincided with an increased tendency towards beta instability. We also compare our results to a randomly selected control sample of non-banks and find some more general effects of regulatory change on individual stock betas.