Tech titans' market heft could signal broader stocks worry

NEW YORK (Reuters) - Outsized stock price gains for Apple Inc and Microsoft Corp mean the two tech titans' shares have attained unusual status: a combined weight of 10% of the benchmark S&P 500 index.For some stock watchers, this is an example of worrisome concentration that could undermine Wall Street's record run. The S&P 500, which many use a proxy for the overall market, is a market-cap weighted index, meaning that large stocks carry more influence.The last time a year ended with two..