NEW YORK, Sept 26 — Pfizer Inc has decided not to pursue what would have been among the largest breakups in corporate history, after years of evaluation and speculation by investors about the future of the US’s biggest drugmaker.

The decision comes after what New York based Pfizer said was “extensive evaluation,” and what had become one of the most closely watched decisions in the industry, since a breakup was first speculated in 2012. It also follows US tax rules that this year blocked Pfizer’s attempted merger with Allergan Plc, which would have shifted the company’s tax address overseas and bulked up units before a breakup.

In recent months, the company had signalled it might stay together.

“By operating two separate and autonomous units within Pfizer we are already accessing many of the potential benefits of a split — sharper focus, increased accountability, and a greater sense of urgency — while also retaining the operational strength, efficiency and financial flexibility of operating as a single company,” Chief Executive Officer Ian Read said in a statement.

The question now is what’s next. Pfizer, in the statement, said it is “poised to grow” both businesses, and the drugmaker most recently agreed to a US$14 billion (RM57.8 billion) deal to acquire Medivation Inc and its cancer treatments.

Investors have been waiting for a decision since 2012, when a Goldman Sachs Group Inc analysts suggested the company should. Soon after, it began reorganising its business into what eventually became two distinct units — one cash-generating business with older and off-patent medicines, and another growth-focused operation with products dependent on more recent research and development.

The shares fell 1.1 per cent to US$33.90 at 6.55am in New York. Pfizer’s stock has gained 52 per cent since March 2012, when the drugmaker indicated it may be willing to consider a breakup. That’s comparable to the 53 per cent increase in the Standard & Poor’s 500 Index in the same period, but well below the 96 per cent jump in the S&P Health Care Sector Index.

The decision doesn’t affect the financial guidance for 2016, which Pfizer reaffirmed. Both units have delivered solid year-over-year performance over the course of the past three years, demonstrating their ability to compete on a standalone basis, Pfizer said. — Reuters