<p>Biotech stocks broke an important psychological barrier last week when a leading index closed below 400 points for the first time since the sector took off in 2000.</p>
<p>The American Stock Exchange biotech index, a basket of 17 leading stocks, closed at 383.34 Friday. The index first passed 400 in January 2000, when biotech stocks soared on excitement over the imminent completion of the Human Genome Project.</p>