The failure hit Lilly (LLY) hard, dragging its stock down by 7.8% by the time the market closed. The drug was the only cardiovascular-focused treatment in the company's portfolio. HDL cholesterol works to transport fatty lipids out of the arteries, helping to guard against heart attacks and strokes. Research has shown that people with higher HDL levels have fewer heart attacks. The idea is that CETP drugs can raise a patient's HDL cholesterol, reducing a patient's risk for heart disease. The market for such a drug is significant: Lilly's evacetrapib was projected to bring in $632.7 million in sales by 2020, according to Bloomberg data. However, the mechanism hasn't proved itself out —for Lilly or other drug makers working on CETP treatments. Lilly was forced to terminate its Phase 3 trial due to lack of efficacy (not safety concerns), costing the company as much as $90 million in lost research and development. Before then, Roche Holding also ended tests on dalcetrapib in 2012 for lack of efficacy.