Alexion Pharmaceuticals (ALXN, news, chart) is seeing spread trading for a second day. Yesterday, we saw an increase in activity in the October 47.5/52.5 bull call spread. Today, the focus is on the October 45s and 50s. With shares trading down $1.95 to $41.81, a block of 2,500 ALXN October 45s traded offerside for $1.57 a contract on the ISE. The same number of 50s traded bidside for 42 cents. Open interest in the 45s is 475 contracts and only 76 contracts of open interest in the 50s. Consequently, like yesterday, today’s volume appears to be opening bull call spread trading in the biotech company. If so, the strategist is paying a net debit of $1.15 and has a potential payoff of $3.85 if ALXN rallies to $50 a share or more by October expiration.

Alexion Pharmaceuticals (ALXN, news, chart) saw seven times its normal trading volume Thursday, as some players seemed to overlook weakness in the stock price and establish bullish spreads on the Cheshire, CT biotech company. Shares fell $2.24 to $43.76 on the day. In the options market, 11,000 calls and 719 puts traded on the day. The day’s top trades included an order for 1,443 October 47.5 calls traded offerside for $1.63 a contract and the same number of 52.5 calls traded bidside for 38 cents. The trade was repeated several times until volume in both contracts surpassed 4,000.

It appears then that one or more players was actively buying bull call spreads. If so, the risk and or cost of the trade is $1.35 with a profit potential of $3.65 if ALXN rallies to $52.50 or more by October options expiration. There was no news on the company Thursday. The company announced Tuesday it will be presenting at the Morgan Stanley Global Healthcare Unplugged Conference in New York City Tuesday, September 9, 2008.