Information provided by Theflyonthewall.com 

Apple (AAPL), a stock that is always in focus, is even more in the spotlight as its Worldwide Developer Conference gets set to kick off Monday with a keynote presentation to be delivered by CEO Tim Cook.

Investors, expecting new announcements about Apple's mobile operating system and its MacBook line, pushed the stock higher by 1.25% about an hour before the event began.

Omnicare (OCR) slid 7% after the company's CEO John Figueroa resigned, though the company said its financial guidance for the current year was unaffected by the resignation and the resulting search for a new permanent CEO.

Among the notable gainers were Micronetics (NOIZ), up 94%, on news it will be acquired by Mercury Computer Systems (MRCY) for $14.80 per share, and ZaZa Energy (ZAZA), up over 30%, as the company modified its agreements with Hess (HES), resulting in payments of $85 million and an increase in ZaZa's net acreage in the Eagle Ford region. ZaZa also said it has engaged Jefferies to seek joint venture partners for some of its shale gas assets.

Also higher were shares of Mellanox (MLNX), up more than 5%, following the selection of its adapter silicon for use in certain Intel (INTC) products.

Noteworthy losers included Centene (CNC), down 25%, after lowering its 2012 earnings guidance due to higher medical costs at several of its subsidiaries, and EnergySolutions (ES), which also lowered its 2012 guidance and declined 53%.