The din of corporate wedding bells was deafening this week as Deutsche Bank swallowed up Bankers Trust to become the world's biggest bank, the pharmaceutical firm Hoechst got hitched to Rhone Poulenc and, in the biggest merger in industrial history, the oil giant Exxon took over Mobil.

Wall Street welcomed the creation of ExxonMobil as a textbook example of how firms ought to get together. But German analysts fear that Deutsche Bank and Hoechst may have been driven into unsuitable alliances by the fusion fever that has gripped European board rooms in recent months.

It all began in the late Spring, when Daimler-Benz and Chrysler astonished the motor industry with the news that they were about to tie the knot. Car manufacturers have been getting bigger and fewer for a number of years but the trend towards mergers is now dominant in almost every sector.

Globalisation and the impending launch of the euro are wiping out many niche markets based on national price differences and giving international firms a big cost advantage. Yet most mergers fail to fulfil the expectations of their progenitors and many recent corporate courtships have run into trouble almost from the start.

Deutsche Bank boss Rolf-Ernst Breuer describes Bankers Trust as "an ideal supplement to the business portfolio of the Deutsche Bank". But many banking analysts suspect that the American investment house's main attraction for the German bank was the fact that it was both available and unassuming.

Although Bankers Trust was founded in New York almost a century ago, it has changed its strategy many times and currently ranks only eighth in the league table of US investment houses. Unlike one of the bigger houses, such as J.P. Morgan, Bankers Trust represents no threat to the identity of Deutsche Bank and the German management will remain dominant.

One symptom of German dominance is the fact that, although the merger will cost 5000 people their jobs, Deutsche Bank employees in Germany will not be affected. London and New York will be the scene of most lay-offs but a Deutsche Bank spokesman told The Irish Times this week that it may be months before the bank's employees in Dublin discover their fate.

"It will depend on each case and where the overlaps are," he said.

Even if the merger is a success, it will do nothing to solve Deutsche Bank's problems closer to home. Mr Breuer's ambition to carve out a dominant position for the bank in Europe will be on hold while he directs his energies towards the Bankers Trust takeover. And, although the fusion holds no fears for the bank's German staff, thousands are worried about the consequences of branch closures and the expansion of telephone banking services.

If a dark cloud hovers over the Deutsche Bank's wedding plans, the omens for the match between Hoechst and Rhone Poulenc are even worse.

Pharmaceuticals and Life Sciences (a catchall term that embraces drugs, agro-chemicals and such borderline areas as genetically modified plants) are the model children of the chemical industry. Profits are huge often as much as 30 per cent of turnover and the market is growing relentlessly.

Despite the Asian crisis, the market for prescription drugs grew by 8 per cent worldwide this year and, in the US annual growth has been in double figures for a number of years.

But Hoechst and Rhone Poulenc are among the industry's most sluggish performers, with high manufacturing costs and a poor share of the crucial American market. Neither has any promising, blockbuster drugs in the pipeline and industry analysts say that the merger will do little to improve matters.

A number of high-profile mergers in the pharmaceutical industry have failed to get off the ground in recent months.

Most mergers fail either for cultural or personal reasons, with senior managers unable to agree a pecking order or management systems refusing to gel. Among the recent pharmaceutical mergers, the most successful has been Novartis - a fusion of Ciba-Geigy and Sandoz. Not only were both companies Swiss, they were both based in Basle - just across the lake from one another.

But the most successful companies - such as Pfizer, the manufacturers of Viagra - have avoided merger mania altogether.