Weak economic data sent stocks to a weak close Friday, to end Q3 on a down note.

The Nasdaq fell 0.7%, the S&P 500 0.5% and the Dow Jones industrial average 0.4%. Volume fell slightly on both major exchanges, according to preliminary data.

The Chicago Purchasing Managers’ Index fell to 49.7 for September, reflecting contraction. The University of Michigan’s final read on consumer sentiment for September also undercut expectations.

GNC Holdings (GNC) rose 5% after JPMorgan reported the vitamin retailer was introducing a special gold card service in several major metropolitan areas. The brokerage said the service could boost same-store sales in those markets, and kept an overweight rating on the stock. Volume came in barely above average.

GNC has fallen for three weeks in a row. But the week saw an upside reversal, with the stock paring what was an 8% loss to just 1%. The stock also regained its 10-week line.

Only a few top-rated stocks fell with heavy volume. Stratasys (SSYS) fell 4%, although in soft trade, and erased the bulk of Thursday’s advance. The stock has cooled off sharply since clearing a cup-with-handle base in July. Stratasys has wiped out its 35% gain from its July 18 breakout.

Apple (AAPL) fell 2% in slightly above-average volume. CEO Tim Cook apologized for the iPhone’s criticized mapping software. Cook even pointed customers to use maps from rivals Google (GOOG) and Microsoft (MSFT). Apple is 8% past a 619.97 buy point from a cup-with-handle base.

TransDigm (TDG) reversed higher, moving from a 2% loss to a 1% gain as volume climbed well above average. The stock cleared a 136.44 buy point from a flat base Aug. 17 in big volume, but hasn’t made much headway since. It’s up about 4% past that trigger.