SiliconBeat

The valley is to lose yet another public company as Catalyst Semiconductor, a fabless maker of programmable semiconductors based in Santa Clara, has agreed to be acquired by ON Semiconductor of Phoenix, Ariz., according to filings early today with the SEC.

The all-stock transaction will give Catalyst shareholders 0.706 shares of ON Semiconductor common stock for each share of Catalyst common stock they own, which represented a value to Catalyst shareholders of $6.24 per share, a premium of 54 percent to where its shares closed Wednesday, and based on a closing price for ON Semiconductor shares of $8.84 that day.

The deal, announced before the markets opened Thursday, was given a thumbs up by investors. Shares of Catalyst (ticker: ONNN) jumped 58 percent to $6.40, while shares of ON Semiconductor (ticker:ONNN) climbed 5 percent to $9.23.

The number of Silicon Valley public companies now stands at 260. That’s down by more than a third of the companies headquartered here at the height of the tech boom in 2000. And at least a dozen of those companies are barely active, with stock prices measured in pennies.