NEW YORK (AP) _ Harold Geneen, who built ITT Corp. into a conglomerate, died after suffering a heart attack. He was 87.

Geneen died Friday at New York Hospital, according to his secretary, Marie Serio. Geneen and his wife lived in Manhattan.

When Geneen became president and chief executive of International Telephone and Telegraph Corp. in 1959, he inherited a loosely knit group of diversified, mostly overseas businesses. Geneen sought to tighten them into one powerful conglomerate while adding more companies at a breakneck pace.

ITT embarked on an ambitious buying spree after Geneen took over, making more than more than 250 acquisitions _ some hostile _ in the 1960s and 1970s. For the most part it didn't matter what the companies produced, as long as they were likely to boost ITT's profits.

The deals included the Sheraton hotel chain, Wonder bread maker Continental Baking, and Avis Rent-a-Car.

ITT's success during that period was attributed to Geneen's relentless management style. Some associates said he sacrificed virtually his entire personal life for his duties at ITT.

``Some people accuse me of being a workaholic. I plead guilty,'' Geneen once wrote.

He retired in 1977. During his tenure, ITT's sales grew from about $700 million to about $17 billion. Its profit leaped from $29 million to $550 million.

Geneen was survived by his wife, June Hjelm Geneen, two sisters-in-law, five nephews and their families. Funeral arrangements were incomplete.