The clock may be ticking for embattled Merrill Lynch ( MER) CEO Stanley O'Neal. The latest rumor indicates that O'Neal may resign as early as Sunday. According to the swirling speculation, Larry Fink -- CEO at BlackRock ( BLK), which Merrill has a 49% stake in -- would replace O'Neal. Sources that the TheStreet.com has spoken with are saying that there is a "90% chance that O'Neal is replaced by Fink." A Merrill Lynch spokeswoman declined to comment and an assistant for Fink at his offices in New York said that he was unavailable to comment. Rumors have been flying fast and furious about O'Neal and his possible ouster after The New York Times reported early Friday that O'Neal angered Merrill directors by calling Wachovia's ( WB) Ken Thompson to broach a possible merger without first consulting Merrill's board. The paper said directors were so angered by the executive's apparent disregard for board authority that they are considering replacing him and even discussed prospective replacements. Rumored successors to O'Neal have run the gamut from NYSE-Euronext ( NYX) head John Thain to Robert McCann, the head of Merrill's global private client business. It remains unclear if anything definitive will happen over the weekend, but speculation has heated up considerably due to O'Neal's recent fumblings. Losses tied to esoteric collateralized debt obligations saw Merrill reporting some $8 billion in write downs Wednesday -- just three weeks after the brokerage firm estimated its losses at a staggering $3 billion lower. The missteps have caused some investors to lose faith in O'Neal, which has led to heavy speculation about his ouster -- and drove Merrill shares up more than 8% Friday.