The private-equity buyout boom has reached into most segments of the economy, providing a potential bid for whatever stock you own.

If private-equity investors are interested in Chrysler, their appetite for risk must know no bounds.

One sector where private-equity firms have not yet made a splash is biotechnology and pharmaceuticals.

That's not to say that biotech is being ignored by private money. Venture capital seed money is finding its way back into biotech start-ups. There's a resurgence of acquisitions of more mature biotech companies by larger firms in the industry.

In sum, venture capital and buyout transactions in biotech hit a record-high $1.31 billion in the first quarter, according to data compiled by Thomson Financial. Two major factors explain recent interest in biotech, said Robert Keiser, a vice president at Thomson Proprietary Research.

"As the broader equity markets have rebounded, you've seen risk appetites increase," he said.

Also, profits by major drug companies have blossomed in recent quarters, and the outlook for the current quarter is strong. Those profits provide cash for making acquisitions.

The recent agreement by drug giant AstraZeneca to acquire biotech developer MediImmune for $15.2 billion reflects the deal-making potential inside the industry.

"There are some tail winds there, where the industry is making for some lost time," Keiser said.

Last year, the health-care sector saw the biggest expansion of merger-and-acquistion activity of any industry group, said Brent Felitto, head of heath-care investment banking at William Blair & Co.

Growth in 2006 doubled from 2005 in transactions and dollar amounts of deals in health-care mergers and acquisitions, he said. As major drug companies seek new products for their marketing pipelines, "biotech is increasingly important to Big Pharma," Felitto said.

What's missing is a headline-grabbing leveraged buyout of a drug or biotech company by a general purpose private-equity firm, said Christopher Raymond, a biotech equity analyst at Robert W. Baird & Co.

"We haven't seen a lot of private-equity moves in biotech or pharma," he said.

That's odd, given what Thomson's Keiser called the "virtuous cycle" in the resurging supply of money for biotech investing and intense demand for biotech expertise.

Seasoned biotech companies should be prime candidates for private-equity firms, which could strip out less profitable projects and sell them to drug giants or through initial public offerings.

The absence of private-equity buyouts of biotech companies might be an impediment to a new round of biotech optimism.

Investment returns on biotech stocks are barely exceeding the benchmark return of the Standard & Poor's 500 index.

Private-equity firms might be hoping for a pickup in enthusiasm toward biotech IPOs, the principal way that private investors can reap investment gains.

Raymond notes that in recent years, returns to venture capital investors who staged biotech IPOs have declined.

"That trend has not been in the right direction; things may change this year," Raymond said.

If they do, private-equity firms could discover the biotech sector.