Business Notes WALL STREET

Even before Black Monday, the First Boston investment firm's go-go days had gone. In late 1986 the company's traders lost $100 million in the Treasury bond market. Last February the firm's prized merger-and-acquisition specialists, Bruce Wasserstein and Joseph Perella, defected to start their own firm, taking 16 staffers with them.

With the firm beset by squabbles over strategy and slumping morale, chief executive Peter Buchanan decided that it needed shoring up. After six months of negotiations, First Boston agreed last week to be taken over in a $1.1 billion merger with its European affiliate, Financiere Credit Suisse-First Boston. The new investment firm, which will be privately held, will be controlled by Credit Suisse, the giant Zurich-based banking company.