Ackman's Pershing Square makes $3.3 billion bet on Valeant

BOSTON (Reuters) - Hedge fund mogul William Ackman has purchased a $3.3 billion stake in Valeant Pharmaceuticals International , making his firm the company's fifth-largest stakeholder, a source familiar with the matter said on Monday.

Ackman's $20 billion Pershing Square Capital Management began building up the 5 percent stake in the Canadian drug-maker this year, only months after his vocal effort to help Valeant buy Botox-maker Allergan failed.

The source, who asked not to be named, said the fund would take a passive approach to Valeant, instead of pressuring it to change management or pursue strategic options as it does with most of its investments.

(Editing by Richard Valdmanis and Chizu Nomiyama)