Here’s what’s hot in the market today: Immucor and Ameron both surged on news the firms may be acquisition targets; networking tools manufacturer NetScout fell after a preliminary earnings report; European airline Ryanair fluctuated amid good and bad news; pizza palace Papa John’s took a slight hit after a SunTrust downgrade.

Immucor (NASDAQ: BLUD) was up more than 30% to reach $27 on 18 million shares. The company, which specializes in products used in blood analysis, agreed to be acquired by TPG Capital for $27 a share, or just under $2 billion.

Ameron International (NYSE: AMN), manufacturer of industrial products like wind turbines, water piping, and fiberglass piping for chemical or oil transport, was up more than 27% to trade above $84. National-Oilwell Varco (NYSE: NOV) said it would acquire Ameron International for $772 million or $85 per share.

NetScout Systems (NASDAQ: NTCT) plummeted 16% to $17.75 on more than 1.5 million shares. The networking tools manufacturer behind products like the nGenius traffic analysis module was hit hard after reporting preliminary earnings results for its most recent quarter that ended on Jun. 30. The company said it will report revenue between $62 and $64 million, well below both its own and analyst expectations for the quarter.

Ryanair Holdings (NASDAQ: RYAAY) fell close to 2% as the U.K.-based airline was fined €500,000 on Monday by the Italian Anti-trust authority. Ryanair had good news today, reporting that it transported 9% more passengers in June 2011 than during the same month in 2010. Shares were trading just above $29.

Papa John’s (NASDAQ: PZZA) fell nearly 5% to about $32.30. The company dipped after SunTrust Banks (NYSE: STI) downgraded the pizza company from “Buy” to “Neutral.”

As of this writing, Anthony John Agnello did not own a position in any of the stocks named here. Follow him on Twitter at @ajohnagnello and become a fan of InvestorPlace on Facebook.