As of July 15, short interest dipped to about 13.058 billion shares, compared with 13.173 billion shares as of June 30.

Investors who sell securities "short" borrow shares then sell them, expecting the stock to fall so they can buy the shares back at the lower price, return them to the lender and pocket the difference. Shorting can also be part of a hedging strategy.

(Reporting by Chuck Mikolajczak; Editing by Mark Porter)