The asset sale and IPO -- Bloomberg data show they took in $6.3 billion in revenue -- could mark a wider breakup effort by Read, who has spoken about Pfizer's re-commitment to its drug research and development as some of the company's key drugs, led by Lipitor, go generic.

Pfizer shares were down less than 1% to $22.56 in pre-market trading. While a year-to-date share rise of just over 4% has underperformed the S&P 500, Pfizer's 18%-plus gain in the last six months has outperformed markets, fueled by the divestiture plans.

In a March meeting, Goldman Sachs analyst Jami Rubin wrote in a report that Read hinted at a multi-year breakup of Pfizer far beyond his previously announced divestiture plans. Health care giants Abbott Laboratories ( ABT) and Covidien ( COV) have been pursuing multi-billion spinoff plans since last year.

"We recently met with PFE's CEO Ian Read, who expressed an openness to going further with separations beyond Animal Health and Nutrition if the conditions make sense... This, coupled with the CEO's openness to consider unlocking further value, could create an attractive situation with significant upside," wrote Rubin of the meeting in a March 27 note to clients.

If Pfizer were to undergo a full breakup, Rubin expects it to occur in three parts, with the sale of the company's animal health and nutrition units as just the first step. In a split, Pfizer would be more focused on its growth-oriented pharmaceuticals business and a stable generics business, argued Rubin, who sees the moves netting Pfizer 18 cents a share in EPS.

After those divestitures, a second step would then be a rationalization of Pfizer's organizational structure after the disposals, with efficiency efforts likely to wrench out a $26 a share stock value that puts Pfizer on Goldman Sachs' "America's conviction buy list."

The final step, a full split of Pfizer's drugs businesses, could come in two to three years' time, with the possibility that the moves drive $5.7 billion in additional sales, adding 93 cents to earnings per share, according to Rubin.

"In our view, Pfizer has emerged a new company, with significant execution still ahead but the important groundwork laid down. While 2011 was clearly a transformative year for Pfizer with sweeping catalysts that unlocked shareholder value, we continue to see significant and stock-moving catalysts ahead," wrote Rubin.

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