The U.S. Securities and Exchange Commission is considering regulatory changes aimed at slowing stock trading during periods of cascading prices, even though the agency hasn’t yet concluded what caused this week’s market plunge, two people familiar with the matter said.

SEC officials are weighing whether uniform trading curbs should be imposed across markets for companies that have fallen a certain percentage, said the people, who declined to be identified because the discussions are preliminary. The agency is examining whether any rules should include a time element because a steep decline that occurs in minutes may be more detrimental to markets than a decline over several hours, one of the people said.

U.S. regulators and exchanges are trying to determine what happened after stocks fell May 6, temporarily erasing more than $1 trillion in market value, in a rout fueled by waves of computerized trading. The SEC and Commodity Futures Trading Commission said in a joint statement yesterday that declines for individual stocks were “inconsistent” with well-functioning markets and pledged to make “structural” changes if necessary.

SEC spokesman John Nester declined to comment on internal agency discussions. Lawmakers are pressing the SEC for answers.