When Abbott Laboratories' (ABT) top product, the arthritis drug Humira, dropped in status from from wildly successful to pretty successful, the logic of Wall Street dictated that something had to be done about it.

Now, the question is whether Abbott has done enough to fully address its Humira "problem" with Monday's agreement to acquire the pharmaceutical unit of Solvay SA (SVYSY) for about $6.6 billion cash.

On one hand, the deal should boost Abbott's earnings and allow the company to expand in emerging markets, while gaining new products that help reduce its dependence on Humira. But at the same time, the Solvay products and research pipeline leave some Abbott investors unimpressed, and Abbott is doubling down on a cholesterol franchise that has clouds hanging over it.

Humira generates about one-sixth of total company revenue but its sales growth has slowed to about 20% this year from nearly 50% last year. The deceleration - fueled by currency fluctuations and high copays for some patients - contributed to a 9% decline in Abbott shares year-to-date through Friday, lagging behind most other big drug makers. A relatively thin late-stage research pipeline also has factored into investor discomfort.

Abbott Chief Executive Miles White - who has been hesitant to publicly acknowledge that the Humira slowdown was much of a problem in the first place - hopes the Solvay deal helps put to rest concerns about the sustainability of Abbott's profit growth.

The Solvay purchase may not definitively address Abbott's heavy reliance on Humira, but it will add to Abbott's earnings, and White indicated Abbott would continue to search for additional deals.

So far on Monday, the market seems happier with Abbott - the stock is up 3.3% at $48.91.

Abbott will pick up more than $3 billion in annualized sales with the Solvay buy, including gastroenterology and hormone-based drugs; in comparison, Abbott had $29.5 billion in sales last year, $4.5 billion of which was from Humira. Also, Abbott will inherit a research pipeline that includes potential treatments for Parkinson's disease - partially addressing what some investors view as Abbott's relatively weak late-stage pipeline.

A question mark is Abbott's doubling down on the fenofibrate drugs Tricor and Trilipix, for treatment of cholesterol-related abnormalities and which Abbott has co-marketed with Solvay. Abbott will gain full marketing control and buy out the royalty rights from Solvay. But Tricor could become exposed to generic competition in the next couple of years, and both drugs could face pressure in coming months if a U.S.-sponsored patient trial raises concerns about their effectiveness, as some doctors and analysts expect.

White said Abbott wasn't particularly interested in broadening its presence in the fenofibrate market at first, but "as time went on we got a fairly good feel for what our future looks like here. Given that, it became easier for us to put it in the deal, which made it easier for Solvay to do the deal."

Analysts had mixed reactions. Bernstein's Derrick Sung said the deal will boost Abbott's bottom line and help it expand into emerging markets. Many pharmaceutical companies have emphasized the need to diversify into emerging markets over the past year, as pressures have mounted on the U.S. prescription-drug market that drove hefty profit growth for many years.

But Credit Suisse's Catherine Arnold, while acknowledging the profit boost, would have preferred to see Abbott pursue "more strategic assets that would add better long-term growth." She said the pressures on the fenofibrate franchise will offset some of the benefits of the deal, and that Humira is still expected to contribute more than one-third of Abbott's sales growth over the next three years.

Abbott isn't finished with deals. White noted the company would inherit $500 million in research-and-development capacity that would give Abbott flexibility to pursue licensing or "external partnering" agreements, and that "we hope to share more news on this front in the coming months."

-Peter Loftus; Dow Jones Newswires; 215-656-8289; peter.loftus@dowjones.com