The Basic Materials sector (XLB) held steady on a trading day that saw S&P 500 drop 0.7%.

The ETF, as a proxy for the sector, tracked closer to the overall market today than over the past month. Entering today's trading, XLB was down 1.3% over the last thirty trading days. The S&P 500, in comparison, went up 1.2%.

Increasing 9.3% (+33 cents) to close at $3.87, Amyris (AMRS) was a major gainer in the sector. Today, 2.4 million shares traded hands. The stock traded in a range of $3.61 to $4.35.

Compass Minerals International (CMP) declined 3% to close at $72.34, moving below its 50-day moving average of $74.23 and 200-day moving average of $73.15. US Steel (X) rose 9.1% to close at $20.65, cross its 50-day moving average of $19.58 and 200-day moving average of $24.34.

Olympic Steel (ZEUS) rose 2.5% to close at $15.65, approaching its 50-day moving average of $15.90. It has also moved closer to its 200-day moving average of $20.01. Encore Wire Corporation (AG) fell 3% to close at $27.40, moving closer to its 50-day moving average of $26.94. Also, the stock moved closer to its 200-day moving average of $16.12.

Ampco-Pittsburgh (AP) was a major loser in the sector, falling 4.9% (-81 cents) to close at $15.71 with 22,624 shares moving. The stock traded between $15.65 and $16.71. The share price has been sliding in the last month, down $2.62 (-14.3%) from $18.33 on June 29, 2012.