An emergency measure protecting a select group of financial stocks from abusive short-selling expires on Tuesday, probably leaving at least a two-month gap before a similar rule, currently being considered, is imposed.

The US Securities and Exchange Commission has said that it would not extend the rule preventing “naked” short-selling in shares of 19 key financial entities, including mortgage groups Fannie Mae and Freddie Mac, and big Wall Street firms that include investment bank Lehman Brothers.