Investors questioned Netflix Inc’s premium valuation after the video-streaming service reported U.S. subscriber additions below its own expectations, a sign that competition from the likes of Hulu is intensifying. Netflix shares fell more than 9 percent to $100.11 in early trading on Thursday. While Netflix blamed the disappointing numbers on the mandated transition to chip-based debit and credit cards, some analysts said the reason seemed unconvincing since these cards have been around for a while.