By Barry S. Cohen, Stock Traders Daily

It appears that while Express Scripts (ESRX) and Walgreen (WAG) were squabbling over contract terms, CVS Caremark (CVS) was laughing all the way to the bank.

In the third quarter, CVS earnings were up 16% from a year earlier, beating analyst estimates. The Rhode Island drugstore operator and pharmacy benefit manager, or PBM, evidently gained and kept many of the Walgreen customers that weren't doing business with Express Scripts because of a dust-up between the two companies. 

In fact, CVS management thinks the Walgreen-Express fiasco added 4 cents to its third-quarter earning per share. Because of the added business, CVS raised its earnings estimate for the full year.

For Walgreen, patching things up with Express Scripts may prove to be too little too late. The drugstore chain could permanently lose some 60% of its Express customers to CVS. That translates into a loss in business of some $4 billion annually and may account for the nearly 6% decline in same-store sales during October. Investors have taken note of Walgreen's issues, driving the stock down nearly 6% in the past month, versus a 1% drop in the DJIA.

Express shares also have been under pressure. Even though the company reported a 21% jump in third-quarter earnings -- thanks in part to this year's acquisition of rival Medco Solutions --Express reduced it guidance for 2013, citing a tougher economic climate. The company can't be pleased that one of its largest customers, UnitedHealth (UNH), is bringing pharmacy benefits management in house. 

With its stock price depressed, I think now may be a good time to grab some Express shares. The company is by far the biggest PBM in the United States and many analysts rate the stock a strong buy or a buy. In fact, before the earnings announcement, three investment firms all reiterated their outperform ratings on Express and had over $70 price targets -- compared to Express's current stock price around $53 -- thanks in great part to the $100 billion sales machine the company is expected to be in 2013.

Analysts also like another company in the PBM business, Catamaran (CTRX). Catamaran has rewarded shareholders with a 60% gain in share price year to date. And even though the company's third-quarter earnings declined due to acquisition-related costs, Catamaran, like Express, raised its earnings forecast for the full year.  

If you're wondering how to trade companies mentioned in this article it would be a good idea to consult the Stock Traders Daily's real time trading reports.