Ebb & Flow

The market's enthusiasm for upside surprises reached new heights last week as shares of Human Genome Sciences Inc. (NASDAQ:HGSI) more than tripled on the back of good Phase III data for a drug that many investors had written off.

The stock tacked on $1.54 billion in market cap as its shares reached levels not seen since the summer of 2002, taking the biotech from the sub-$500 million small cap space to $2 billion in valuation...