Topping the list of the best performing sectors this afternoon is the Biotech HOLDRS Trust (BBH), boosted in part by Genentech (DNA) gaining more than 13% on news that Swiss drug giant Roche Holding will buy 44% of the company it doesn't already own for $43.7 billion. Also seeing a boost is the Market Vectors Coal ETF (KOL) on rumors that the Russian mining giant Mechel may be looking to acquire a North American coal company. On Friday, Reuters reported that Mechel plans to use the money raised from its share sale on Wednesday to acquire a large private mining company abroad. This rumor has helped give the sector a lift this afternoon.

Meanwhile, the Internet HOLDRS Trust (HHH) has been pulled lower by weakness in Yahoo! (YHOO) following news that Carl Ichan has been named to its board in return for an end to his campaign to take over the company. Shares of the Internet giant are down more than 2% this afternoon on concerns regarding its ability to survive as a standalone company.