Electro-Sensors (ELSE) agreed to be acquired by steute Technologies for $7.75 a share, a premium of about 75% to the closing price on Monday.

The stock surged 72% as intraday volume topped 361,700 shares versus the daily average of 2,909.

UnitedHealth Group (UNH) raised its full-year earnings outlook after the health insurance giant recorded an unexpected increase in Q1 results.

The stock rose 8.4% as volume topped 17.6 million shares versus the daily average of 10 million.

Aevex's (AVEX) director Brian Raduenz purchased 50,000 shares of the company for $1 million on April 16.

The stock advanced 7.5% as volume topped 4.5 million shares versus the daily average of 15.8 million.

Price: 7.62, Change: +3.19, Percent Change: +72.16