(Reuters) Hedge fund veteran William Ackman has the support of some of Wall Street’s top investors as he tries to pull off the biggest-ever deal carried out by a blank-check acquisition company, according to regulatory filings published in the last few days. Among the heavy hitters rounded up by Ackman for his Pershing Square Tontine Holdings Ltd investment vehicle, according to the filings, are mutual fund giant T. Rowe Price Group Inc, investment firm Guggenheim Partners