It looks like the Securities and Exchange Commission will be spending a lot more time digging into the mess surrounding Bears Stearns’ collapse.

The agency received two letters in less than a week calling for separate probes related to the now-acquired investment bank: one asking why the SEC didn’t take enforcement action against it last year, and another asking the SEC to widen its probe into abusive short selling of Bear Stearns’ stock.

The first request came from U.S. Sen. Chuck Grassley, ranking Republican on the Senate Finance Committee. Grassley called on the SEC’s inspector general to investigate why the Enforcement ...