Like banks, insurance underwriting firms vary widely in size, ranging from several large national insurers to numerous small local or technically specialized firms. Investment banking has been more heavily concentrated for some time, no doubt in part reflecting the greater geographic expanse of the markets for their services.
In the past two decades, some degree of consolidation has also occurred across different segments of the financial services industry. During the 1980s and 1990s, as the Federal Reserve modified its regulations, many bank holding companies established so-called section 20 subsidiaries to carry out securities activities that had not been permitted within banking organizations since passage of the Banking Act of 1933, or Glass-Steagall.