Allen Klein, a cunning record executive whose clients included the Rolling Stones and the Beatles and who was known as the “toughest wheeler-dealer in the pop jungle,” but whose ego and temperament also contributed to the breakup of the Fab Four, died July 4 at his home in Manhattan. He had complications from Alzheimer’s disease. He was 77.

Klein was an accountant by trade and fell into musician and record company management by accident. Through his company, Abkco, Klein built his reputation on shrewd attention to financial detail. He ruthlessly negotiated rich contracts for his clients — and for his own gain. He was the target of scores of lawsuits by clients and associates while making millions of dollars for many others.

“Don’t talk to me about ethics,” Klein said in a 1971 interview with Playboy. “It’s like a war. You choose your side early and from then on you’re being shot at. The man you beat is likely to call you unethical. So what?”

After early work for Sam Cooke and Bobby Darin, Klein was hired by Rolling Stones manager Andrew Loog Oldham in 1965 to renegotiate the Stones’ record contract with Decca. He used his thick New Jersey accent and swaggering attitude to impress the group.

“Andrew sold him to us as a gangster figure, someone outside the establishment,” Mick Jagger said in Stephen Davis’s book “Old Gods Almost Dead: The 40-Year Odyssey of the Rolling Stones.” “We found that rather attractive.”

In the early 1970s, Klein used his accounting skills to purchase the entire 1960s back catalogue of the Rolling Stones master recordings from Oldham without the band’s knowledge. Klein also transferred more than $1 million of the Stones’ earnings into his personal account.

Klein saw his greatest aspiration realized when he became manager of the Beatles in 1969. He was aware that Apple Corps, the band’s multimedia company, was months away from bankruptcy and set up a secret meeting with John Lennon and Yoko Ono. From that conference, Klein negotiated a contract to be the group’s business manager.