Efficient Networks (EFNT) was down 35.6% in preopen Island trading. After the close Tuesday, the broadband-access company warned that second-quarter revenue would be below previous forecasts because two major customers did not place expected orders.

Deutsche Banc Alex. Brown

downgraded it Wednesday to buy from strong buy and slashed its 2001 earnings estimate to 10 cents per share from 80 cents.

Robertson Stephens

also cut earnings estimates and downgraded Efficient Networks and several other broadband stocks to long-term attractive from buy.

Among those downgraded are

Copper Mountain

(CMTN)

, down 8.1% in preopen trading;

Paradyne

( PDYN), down 3.2% and

Tut Systems

( TUTS) down 8.9%.