Chipmaker Altera ( ALTR) today raised the floor of its sales guidance, saying it now expects June quarter revenues to be 3% to 4% above the March level.

On April 29, Altera had forecast sequential revenue growth between 1% and 4%, to between $197 million and $203 million.

Leading up to today's update, analysts were looking for sales in the midpoint of that range, at $200.4 million, with earnings of 9 cents.

In a release after the close, Altera said demand is growing for its Stratix, Stratix GX, and Cyclone products.

Altera closed regular trading up 19 cents, or 1%, to $18.55. After hours, shares were up 8 cents, or 0.4%.

Meanwhile, today Soundview Technology analyst Tristan Gerra downgraded shares of both Altera and rival Xilinx ( XLNX) from outperform to neutral.

"This is more of a trading call than a view on long-term fundamentals," he said in a note, pointing to what he called "lofty" valuations.

Both stocks have run up considerably since February, he added. Altera and Xilinx respectively trade at 40 times and 34 times calendar 2004 earnings estimates -- in other words, they're priced at levels 40% and 80% above their five-year median forward P/Es.

Yet Gerra says his research shows weaker-than-expected trends at U.S. distributors overall and decelerating May sales.