Brocade

was down 18.3% in preopen

Island

trading. After the close Wednesday, the company posted first-quarter earnings of 13 cents per share, beating the Street's estimate of 12 cents and the year-earlier 2 cents. The network switch maker said sales also beat the Street's estimate.

But Brocade warned that second-quarter growth would be "very modest" at best and perhaps flat with the first quarter.