Also. . .

* British Petroleum Co. and U.S.-based Amoco Corp. completed their merger, creating Britain’s biggest company and one of the largest oil concerns in the world. BP is acquiring Amoco for about $55 billion and forging a new company, BP Amoco, with a market capitalization of more than $140 billion.

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* Host Marriott Corp., the fifth-largest U.S. hotel company, said it completed the $1.5-billion purchase of 12 luxury hotels from closely held investment fund Blackstone Group. Bethesda, Md.-based Host Marriott also said it will become a real estate investment trust today. As a REIT, Host Marriott will be able to shelter income from taxes as long as it pays out most of its earnings as dividends to investors.

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* Beverly Hills-based Hilton Hotels Corp. completed its split into two hotel and gambling companies and said that the new gambling company had acquired the Mississippi casino operations of Grand Casinos Inc. The newly formed gambling company, which becomes the world’s largest with casino operations in New Jersey, Mississippi and Las Vegas, is known as Park Place Entertainment Corp.