Stocks held strong gains and were near session highs Thursday, cheered on in part by strength in overseas markets overnight and an unexpected drop in wholesale prices. The Nasdaq jumped 1.3%, while the Dow Jones industrial average and S&P 500 added 1% each. NYSE and Nasdaq volume were tracking very close to Wednesday’s levels. In economic news, weekly jobless claims hit a near 15-year low, while wholesale prices unexpectedly fell.