In their letter, the lawmakers, led by Jack Reed, a Democrat, and John Kennedy, a Republican, requested "a thorough examination of any unusual trading, including any atypical options trading, for violations of insider trading law."
"We request that you spare no effort in your investigations and in enforcing the law to the fullest extent," the lawmakers said.
'Brazen Failure'
The Federal Bureau of Investigation has already said it was investigating the Equifax hack. A spokesman for SEC Chairman Jay Clayton declined to comment.
Acting FTC head Maureen Ohlhausen declined to say if that agency was investigating the breach. "We're trying to get a handle on the scope of all of this. We're certainly taking this very seriously," she told reporters at an antitrust conference.
The agency has historically probed big breaches but only sued companies that had been sloppy in protecting consumer data.
The breach also prompted expressions of concern from U.S. Treasury Secretary Steven Mnuchin, while the Massachusetts attorney general said her state planned to sue.
Hackers pilfered names, birthdays and addresses, as well as Social Security and driver’s license numbers - a treasure trove for identity thieves. Data of up to 143 million people may have been exposed.
Following revelations of the stock sales by Chief Financial Officer John Gamble and two other people, Equifax said in a statement last week that the executives were not aware that an intrusion had occurred when they sold their shares.
Massachusetts Attorney General Maura Healey said she intended to sue Equifax with allegations of failing to maintain appropriate safeguards to protect customers' data, including that of nearly three million Massachusetts residents.