Shares of TSI Corp. (NASDAQ:TSIN) dropped $1.25 Thursday toclose at $4.13, with more than 2 million shares changing hands.Cowen and Co.'s biotechnology group, led by analyst DavidStone, downgraded its rating on the Worcester, Mass., companyfrom "neutral/outperform" to "neutral/neutral." (Thedesignations refer to short-term/long-term marketperformance estimates.) Cowen and Co. changed the rating dueto its estimates for lower earnings for the company in the1993-1995 period.

In other market activity, Biogen Inc.'s stock (NASDAQ:BGEN)dropped $4.25 a share to $39.25, with 1.8 million sharestraded. A spokeswoman for the Cambridge, Mass., companysaid the company did not make any announcements and didnot have an explanation for the stock's activity.

The AMEX Biotechnology Stock Index was down 3.27 points toclose at 167.9, while the Chicago Board Options ExchangeBiotechnology Stock Index dropped 2.45 points to 153.3.

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