Aeroflex (ARXX) was down 31.4% in late trading after falling as much as 41% earlier in the session.

The microelectronics company was downgraded to buy from strong buy by

U.S. Bancorp Piper Jaffray

. The move was prompted by concerns about a near-term slowdown in the fiber-optic industry.

Aeroflex makes thin film for the optics market.