PHARMACEUTICALS

Drug Maker’s Shares Tumble: Chiron Corp. shares fell 4.5% after the company said it will cut staff at its plants in Puerto Rico and Amsterdam to reduce production of its multiple sclerosis drug Betaseron. The Emeryville, Calif.-based biotechnology company said the cuts are part of efforts to control costs. Chiron said it expects to take a charge in the first quarter, but that operating expenses will be reduced in subsequent periods. Its shares fell 2 1/2 to close at 53 1/2, after touching 52 1/2 earlier in the day. There were 995,400 shares traded, almost double its recent daily average.