Shares of Eli Lilly were taking a 6.9% hit toward a two-month low in recent trading, enough to make them the S&P 500's biggest decliner. The problem is that the drug giant provided fourth-quarter revenue guidance that was below Wall Street expectations,

Eli Lilly (LLY) agreed to acquire an experimental treatment for breast cancer and other advanced solid tumors from Scorpion Therapeutics for up to $2.5 billion. The purchase price includes an upfront payment and subsequent amounts that Scorpion's shareholders would receive as certain regulatory and sales milestones are achieved.