It seems you got the figure wrong, it's $11B added to DNA's mkt. cap.
Genentech surged nearly 25 percent, or $10.92, to $55, adding almost $11 billion in market capitalization in the last hour of trading, after the National Cancer Institute said Avastin helps lung cancer patients live longer when combined with standard chemotherapy. The American Stock Exchange Biotechnology index (AMEX:^BTK - News) rose nearly 5 percent.