KARACHI (AP): Growing economic and political uncertainty pushed Pakistani shares to new depths on Thursday and triggered violent protests at the Karachi Stock Exchange.

By Thursday afternoon, the exchange's benchmark 100-share index was down 4.2 percent at 10,056 points. The index is at an 18-month low and has fallen about 36 percent from an all-time high in April.

With share values dropping for the 14th straight day, officials said more than 200 small investors, some of whom rent small offices in the exchange building, gathered in its main hall to demand a halt in trading.

When the exchange administration declined, some protesters smashed windows in the exchange and nearby banks, said Mohammed Aslam, the exchange's security chief.

An Associated Press reporters saw broken lights and window panes littering the floor of the exchange. Television footage saw police shooing the demonstrators away from the building.

Pakistani shares are tumbling amid doubts about the three-month-old government's ability to survive economic problems including runaway inflation and wide trade and budget deficits.

The uncertainty is compounded by growing U.S. pressure to clamp down on militants launching attacks into Afghanistan, casting doubt on the government's hopes of negotiating peace deals to curb rising Islamic militancy also threatens Pakistan.