In this video, Motley Fool health care analyst David Williamson gives us the story behind two big biotech jumps today and two big stumbles. Sequenom ( NAS: SQNM ) continues its rally from Friday with more good news that its RetnaGene AMD accurately predicts the progression of wet age-related macular degeneration; this has shares up an additional 8% on top of Friday's 19%. Repros Therapeutics ( NAS: RPRX ) also up today ahead of presenting both of its phase 2 drugs, Androxal and Proellex, at the Lazard conference tomorrow. Meanwhile, Cyclacel ( NAS: CYCC ) and Transcept ( NAS: TSPT ) are both down today after disappointing earnings releases. While you can certainly make huge gains in biotech and pharmaceuticals when these stocks make big jumps, the best investing approach is to choose great companies and stick with them for the long term.