NEW YORK, Sept 24 (Reuters) - Short interest on the

Nasdaq rose 1.1% in mid-September, the exchange said on

Wednesday.

As of September 15, short interest rose to about 17.146

billion shares, compared with 16.959 billion shares as of August

29.

Investors who sell securities "short" borrow shares and

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.