Drug developer Bristol-Myers Squibb (NYSE:BMY) is rapidly becoming the Paris Hilton of the large-cap pharmaceutical stocks. It has been in and out of the news lately, garnering a lot of publicity for both its good and bad deeds. Today, shares of BMY were up more than 5% on the latest rumors and speculation of a potential takeover by partner Sanofi-Aventis.

Just like Paris Hilton, Bristol-Myers has been rumored to be getting together with nearly every other pharma star out there. In 2002, the takeover talk was with GlaxoSmithKline (NYSE:GSK). And just last quarter, shares jumped on the gossip about a potential merger with another pharma after interim CEO James Cornelius came on board, since he filled the top spot at Guidant when Boston Scientific (NYSE:BSX) acquired it.

The latest BMY merger mania arrived today, after a French newspaper reported that Sanofi-Aventis (NYSE:SNY) and Bristol-Myers were in preliminary talks about a possible merger. If a merger with Sanofi does go through, it makes sense for both companies from an operational perspective, as they are marketing partners on the hypertension drug Plavix.

Plavix is by far Bristol-Myers' top-selling drug, bringing in $3.3 billion last year. The drug accounted for nearly a fifth of BMY's $17.9 billion in revenue for the year, despite the brief entrance of a generic competitor, which hurt sales to the tune of an estimated $700 million-$750 million.

Even if both companies are in favor of a merger, it will be interesting to see how the French authorities decide to handle things. They've meddled in the past when foreign pharmaceutical companies have tried to merge with French assets. You only have to go back three years to 2004, when Sanofi and Aventis merged, to find evidence of this.

Originally, Aventis fought off a hostile bid from fellow French pharma Sanofi. The threat of generic competition for Sanofi's Plavix was one of the main sticking points of concern for Aventis when it first shied away from a Sanofi takeover back in 2004.

Aventis was hopeful for a takeover by Swiss drug maker Novartis (NYSE:NVS), but the French authorities said "non" to any potential merger with a foreign firm. Novartis withheld from the bidding, despite numerous proclamations that it would bid on Aventis if the French authorities would give it the d'accord to do so.

Since Bristol-Myers is the more junior of the two pharmas, French authorities will probably have much less concern over any merger between the two companies. With a combined value of more than $170 billion, BMY and Sanofi would be among the top four pharmaceutical firms by market capitalization, on par with Pfizer (NYSE:PFE), GlaxoSmithKline, and the more diversified Johnson and Johnson (NYSE:JNJ).

Who is the winner in a Bristol-Myers and Sanofi-Aventis merger? It obviously depends on the price Sanofi is willing to pay for BMY. But both companies share the same fate in the courts over Plavix, and Sanofi is also awaiting a verdict on the validity of its patents for its top-selling drug, the blood clot treatment Lovenox. Depending on how the verdicts in these cases go -- and assuming Sanofi pays BMY shareholders with shares in the combined company rather than with cash -- the deal could get really expensive for Sanofi shareholders if it's finalized after the verdicts in these cases are announced.

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Fool contributor Brian Lawler does not own shares of any company mentioned in this article. The Fool has a disclosure policy.