The company, also known as SMSC, is the Island's 15th largest by stock market value. It employs about 1,000 workers, including roughly 315 here, and sells integrated circuits and wireless components to computer makers and auto companies, including Porsche, Toyota and BMW.
The buyer, Microchip Technology Inc. of Chandler, Ariz., has agreed to pay $37 per share. The sale is scheduled to close in the third quarter.
Gordon Parnell, vice president of business development and investor relations for Microchip, said it was "too early to share details" on how the acquisition would impact Standard Microsystems' operations on Long Island.
Officials at SMSC didn't respond to requests for comment. Anytime an out-of-state firm buys a local company, officials worry the Island's economy will suffer. Even without job losses, corporations based elsewhere are less likely to donate to Long Island charities, encourage their executives to volunteer at local nonprofits or hire local firms for services such as in-house training.
"There are a lot of secondary impacts that might not be apparent at first glance," said Pearl M. Kamer, the Long Island Association's chief economist.
The acquisition is one of the largest of a Long Island technology company in recent history. In 2007, Motorola paid $3.9 billion for Symbol, a Holtsville-based firm that produced bar-code scanning systems. That same year, one of Long Island's largest defense electronics contractors, EDO Corp., was acquired by ITT Corp. of White Plains for about $1.7 billion.
SMSC was founded in 1971 by Paul Richman, a semiconductor physicist and pioneer in the chip industry, with $1,000 in backing from Long Island venture capitalist Herman Fialkov. The firm devised a process to shrink the size of chips without sacrificing processing speed, allowing computers and other devices to become smaller and more efficient.
SMSC's president and chief executive, Christine King, took charge in 2008. Previously, the former IBM executive ran AMIS Holdings Inc., an Idaho circuits maker, which she sold for $915 million to ON Semiconductor Corp. of Phoenix.
In 2006, SMSC reached a 10-year deal with the Suffolk County Industrial Development Agency to receive tax breaks on its Hauppauge headquarters, which it now leases. As part of the deal, SMSC could owe the county up to $85,000 if it leaves Long Island before 2016.
"But we would make every effort to try to keep the jobs here," IDA deputy executive Tony Catapano said.
SMSC's stock soared 38.83 percent Wednesday to $36.43. Trading was heavy, with 15 million shares exchanged, compared to an average of 128,000.