The Wall Street Journal on 20th May that the SEC over 5 fiscal years that ended in September 2018 only obtained 55% of the $20 billion in enforcement fines set through settlements or court judgments, according to agency statistics. During the prior 5 years, from 2009 through 2013, the SEC collected on 60% of $14.6 billion. The lowest recovery rate was in 2018 just 28% of almost $4 billion, said to be due in part to an unusual $1.7 billion settlement with the Brazilian oil company Petrobras that may never require payment to the SEC. The article says that the SEC has struggled to get defendants to pay more of their fines, although some are almost certain to avoid payment forever. This includes people who went to prison on related criminal charges, or people behind Ponzi schemes who spent the funds they took from defrauded investors.
https://www.wsj.com/articles/some-securities-fraudsters-escape-paying-sec-fines-11558344601