WASHINGTON — The Securities and Exchange Commission is extending the public comment period for possible approaches to rein in short selling and may be leaning toward one of the two main alternatives being considered.

The SEC said Monday it was extending the period, originally slated to end June 19, for 30 days to gather views specifically on that alternative: allowing short sellers to come in only at a price above the highest current bid for the stock. That is known as an upbid rule, and it most closely resembles the Depression-era uptick rule that was abolished in mid-2007.

Investors and lawmakers have clamored for the agency to put new brakes on trading moves they say worsened the market's downturn starting last fall. Short-sellers bet against a stock. They generally borrow a company's shares, sell them, and then buy them when the stock falls and return them to the lender — pocketing the difference in price.

The SEC commissioners now are expected to make a final decision in late fall.