There's plenty of good news for Amgen (AMGN: sentiment, chart, options) shares this morning. The biotech stock was added to the "conviction buy" list at Goldman Sachs, and S&P revised its outlook on AMGN from "negative" to "stable." Thanks to these bullish reports, the security climbed to a fresh 52-week high of $64.99 earlier today. At last check, AMGN was up about 2%.

Bullish option traders are likely cheering today's brokerage boost. The International Securities Exchange reports that traders have snapped up nearly 3 times more calls than puts on AMGN during the past 10 trading days.

However, at midday, it's put volume that's dominating the options pits. The August 62.50 contract has seen 3,239 contracts change hands, and the September 52.50, 60, and 62.50 strikes have seen more than 2,000 contracts apiece cross the tape. Meanwhile, the most active call among near-term options is the September 65, which has seen volume of 2,255 contracts so far.

Today's surge has pushed AMGN through the recently resistant 64 level, which capped the stock since late July. From their March low of $39.16, the shares have raced 63% higher. AMGN's rapid rally spooked many short sellers out of their bearish stance, with short interest on the shares dropping by 35% from its mid-June peak.

This burst of short-covering likely exacerbated the stock's gains. Back in early July, AMGN gapped above its 10-week moving average. The shares have since continued to soar, and are now trading about 21% above this intermediate-term trendline.