Updated from 8:54 a.m. EDTFrench-German drugmaker Aventis ( AVE) has given up the fight and agreed to be acquired by France's Sanofi-Synthelabo ( SNY), triggering declines in the shares of both companies. The sweetened cash-and-stock deal, which came together Sunday, is worth about $55.3 billion euros, or $65.34 billion, and creates the world's third-largest drugmaker, behind Pfizer ( PFE ) and GlaxoSmithKline ( GSK). The offer is worth 66.63 euro, or about $79.29, a share. Aventis had been resisting a deal since late January, when Sanofi first offered 47.8 billion euros, or approximately $60 billion, which it rejected as inadequate. Switzerland's Novartis ( NVS ), which Aventis had courted as a possible white knight, decided not to bid, even though it made a public statement last week saying it was involved in negotiations to buy or merge with the French-German company. Aventis shares fell $5.04, or 6.3%, to $74.72, while Sanofi's slid $1.86, or 5.7%, tO $30.97 in U.S. trading. Novartis shares, however, jumped $2.24, or 5.3%, to $44.67, close to their 52-week high. Sanofi's takeover play had the support of the French government, which wanted to create a so-called national champion in the drug sector. The deal will deliver about $1.89 billion in cost savings, or what Sanofi called "synergies," by 2006.