Maybe they were just too tempting a target. After the runup many of the first tier and top second tier stocks have had over the past few months, it was inevitable that investors would want to start locking in some profits. The question was simply when. So now they've done it - though, importantly, they bought back in on Friday. What's next?

Timely reminder

If we knew the answer to that question, we'd pack our bags and go home. But last week's little scare is useful as a timely reminder that no matter what happens in the stock market, the business of biotech is just that - business. As we've muttered many times before, in the long term, companies will ensure high prices and access to equity by building value. In the short term, forget it - fundamentals are often separate from trading behavior.