A hike in suspicious trading ahead of corporate buyouts led the SEC to file 47 insider trading cases in 2007 – more than in the entire decade of the 1990s.

In its biggest insider trading case this year, the SEC caught a 14-person ring that netted more than $15 million in profits and included three hedge funds, as well as a UBS research executive, a Morgan Stanley compliance lawyer, a Bear Stearns stockbroker, and a day-trading firm.

Insider trading is likely to remain a focus in 2008 as well. The SEC has been scrutinizing executives' 10b5-1 trading programs, which let managers sell company shares without being accused of insider trading. The plans require participants to set up trades before gaining confidential information that may affect stock prices.

The agency also recently started an insider trading probe of hedge funds .

Meanwhile, the rise in the total number of enforcement cases – 656 this year compared to 574 in 2006 – comes amid a federal probe of companies that backdated stock-option grants. Overall, improper financial disclosures, including misleading statements on options grants, comprised 33 percent of all cases.

More than 220 companies disclosed internal or federal investigations into whether they backdated employee stock options.

Complaints against financial advisers made up 12 percent of all SEC cases, just under last year's 15 percent. Cases targeting broker-dealers reached 14 percent from 13 percent the previous year.