Stocks closed mixed Friday and down for the week despite a promising start Monday and Tuesday. Weakness in semiconductor, solar and drug stocks weighed on the Nasdaq, which finished down 0.6%. The Dow Jones industrial average led with a 0.3% gain, boosted by a 4% surge in Nike (NKE), which reported late Thursday. The S&P 500, meanwhile, was down a fraction. Preliminary numbers showed volume was higher across the board.