WASHINGTON (Reuters) - Big investors will be required to disclose their short positions to the US Securities and Exchange Commission under an interim final rule issued by the SEC.

The commission said short-sale reports provide it with important information about sizes and changes of short sales.

The SEC rule extends a temporary short sale disclosure rule until August 1, 2009 to give the agency time to solicit public comment and fine tune details such as whether to publicly reveal the short positions.

The SEC started collecting data on the number and value of stocks shorted by managers who invest more than $100 million under an emergency order issued in mid-September.

The emergency rules, which also included a ban on short selling in more than 950 companies, were issued to help restore equilibrium to markets rocked by fears of a complete financial meltdown. The short sale ban expired earlier in October.

Short-sellers borrow stock they expect will fall in price in the hope of repaying the loans for less and pocketing the difference. They have been blamed by corporate executives for driving down the price of their companies' stock.