By choice or by coincidence, three European drug giants will issue their first-quarter earnings reports Thursday, giving investors a chance to see what years -- or even decades -- of mergers and acquisitions have done for their share prices and growth prospects.

All of the companies are products of multiple, mega-mergers. On Wall Street, the verdict on their performance is mixed, as U.S. analysts evaluate the immediate past of stock price performance and the immediate future of recommendations for buying, holding or selling shares.

And in the latest twist, one of the companies, Strasbourg, France-based Aventis ( AVE) earlier this week reluctantly agreed to a hostile takeover from rival French drugmaker. Sanofi-Synthelabo ( SNY),which would create the world's third largest drugmaker.

Aventis had hoped to do a friendly deal with Swiss drug giant Novartis ( NVS), which happens to be the product of the 1996 merger of Ciba-Geigy and Sandoz. Aventis, itself, is the 1999 creation of a cross-border marriage between France's Rhone-Poulenc and Germany's Hoechst, both of which acquired several other drug companies over the years.

No U.S. drugmake expressed an interest in Aventis.

Nevertheless, the takeover soap opera has been good for Aventis' investors. Like other large foreign companies, Aventis' American Depositary Receipts trade on the New York Stock Exchange. For the 12-month period ended April 22, Aventis' ADRs are up 69% compared to the 25% gain of the S&P 500 and the 8.6% gain by the Amex Pharmaceutical Index of 15 large U.S. companies. Aventis' shares started rising significantly in mid-November, when takeover speculation began.

Novartis' shares rose 9.7% during this period while Sanofi-Synthelabo's shares had gained 13.9%.

Two other multinational drug giants reporting first quarter earnings on Thursday also have been manufactured by big mergers.

There's AstraZeneca ( AZN), the result of the 1999 fusion of Sweden's Astral and Britain's Zeneca Group.

And there's GlaxoSmithKline ( GSK), which has gone through so many changes that a printout from the company's website contains more than four pages of corporate history with names such as Smith, Kline & French, Beecham, Burroughs Wellcome and, of course, Glaxo, which was the name of a dried milk product before it became the name of a company.

GlaxoSmithKline was one of the names bandied about by analysts as a potential suitor for Aventis. GlaxoSmithKline's ADRs were up 10.8% for the 12 months ended April 22; AstraZeneca's shares made consistent gains during the period, rising 34.7%.

Looking to the future, U.S. analysts offer no clear consensus on these big European drug companies. None is as loved as Pfizer ( AZN). But none is as unpopular as Bristol-Myers Squibb ( BMY).

Of four U.S. analysts following Aventis, three recommend holding the stock and one recommends buying it even though the company has beaten Wall Street earnings-per-share estimates for three consecutive quarters, according to Thomson First Call.

GlaxoSmithKline earns a split decision ? three buys, four holds, one sell.

AstraZeneca gets six buys, three holds and three sells despite its strong share price gain in the last 12 months.

Novartis appears to have fared best among the giant European drug companies despite its shares' paltry past performance. Five U.S. analysts have buy recommendations; five have hold recommendations. Among U.S. analysts, Sanofi-Synthelabo has one buy rating and one hold rating.

And for those of you keeping score on Thursday, the Thomson First Call consensus for GlaxoSmithKline's first quarter predicts earnings of $2 billion, or 69 cents a share, on revenue of $9.43 billion. Key issues include the degree of damage caused by generic competition against the antidepressants Paxil and Wellbutrin SR as well as the sales progress of the asthma drug Advair.

The prediction for AstraZeneca is earnings of $894.6 million, or 53 cents a share, on revenue of $5.16 billion. One item of big news will be how well Crestor has performed in the competitive cholesterol-fighter category known as statin drugs. Crestor entered the U.S. market in September. Another key revenue test will be whether Nexium, for acid reflux disease, can grow against competition from branded and generic products.

As for Aventis, the consensus calls for earnings of 89 cents a share; but quarterly sales and net earnings predictions were not available. Non-merger news will focus on how brand name and over-the-counter competition affects the allergy drug Allegra and how U.S. insurance reimbursement affects sales of the cancer drug Taxotere as it competes against lower-priced generic versions of Taxol.

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