If either offer is accepted, it will be the biggest merger deal in history.
The merger deal was expected to be completed in the fourth quarter of 1996.
The four are among the nation's most active advisers on merger deals.
The $3.7 billion merger deal was announced in February 1995.
Foreign investor groups are also becoming interested in the merger deal.
The merger deal was expected to be completed by the third quarter of 1997.
The company said today that with the merger deal now off, it would focus on making its existing business profitable.
Analysts said it had taken a year to 18 months for several health care companies to get back on their feet after big merger deals.
The two companies also said that the merger deal might not close until early in 2001.
It was days from presenting a merger deal to its board.