The SEC could still have a case - timeline, corroborating intrigue, etc. - but as an underfunded revolving door, there's little pushing them to even try to hold these firms accountable. The exchange between a congressperson/senator and an SEC rep a few years ago - "How many cases do you take to trial?" "It's more efficient for us to settle," or something along those lines - was pretty damning. (I apologize, the exact details escape me and every single search function on the internet has apparently been degraded into uselessness.)