The tumble in Argentine stocks that sent valuations to an almost four-year low has spurred Morgan Stanley Investment Management and BlackRock Inc. to buy. Timothy Drinkall, whose Morgan Stanley Frontier Emerging Markets Portfolio rose 26 percent in the past 12 months, said he bought Argentine shares last year after avoiding the country altogether earlier in 2012. By Dec. 31, the nation's equities accounted for a larger percentage of holdings than were in the fund's benchmark index, he said in a Jan. 23 phone interview.