UPDATE 1-U.S.-based stock funds attract $7.6 bln over week -Lipper

(Adds additional flows, analyst comment) By Sam Forgione NEW YORK, July 31 (Reuters) - Investors in U.S.-based funds poured a net $7.6 billion into stock funds in the week ended July 30 on optimism that U.S. stocks could climb further, data from Thomson Reuters' Lipper service showed on Thursday. The net inflows were the biggest in seven weeks and reversed the prior week's net outflows of $7.6 billion. All of the inflows went into exchange-traded funds, which attracted $7.9 billion,