Applied Micro Circuits ( AMCC) resisted raising its first-quarter revenue forecast despite an increase in bookings beginning in April, but that was enough for investors to bid up the stock.

Dave Rickey, the chairman, president and chief executive of the integrated circuits maker, said Thursday that he won't alter the company's outlook for the quarter. In April, the company said sales would be flattish, plus or minus 10% with the fourth-quarter revenue level of $20.1 million.

While the company saw an increase in bookings of an undisclosed amount in April, Rickey said that, "given concerns that abound in our end markets, we are not ready to call this any meaningful trend. To reiterate, we are not altering our guidance at this time, but are encouraged by the bookings momentum so far this quarter."

Analysts polled by Thomson First Call expect the company to report revenue of $20.3 million in the first quarter. Excluding charges, Applied lost 5 cents a share in the first quarter last year, with sales of around $30 million.

Applied's shares rose $1.05, or 18.6%, to $6.69 during Thursday afternoon Nasdaq trading.