by BBC News Online's Brian Wheeler

Merger mania went into overdrive this year, as British companies battled to keep pace with fast-consolidating world markets.

The year began in spectacular style with the �112bn merger of Vodafone, Britain's biggest company, with German conglomerate Mannesmann.

The deal was trumpeted as the biggest in corporate history, a title later claimed by the proposed marriage of AOL and Time Warner in the US, which took until December to clear regulatory hurdles.

UK pharmaceutical giants SmithKline Beecham and Glaxo also took a year to gain clearance from US watchdogs for their �120bn merger, which will create the world's largest drug company.

Global stock market

However, the battle for control of the London Stock Exchange (LSE) - seen by many as part of a wider move towards a 24 hour global stock exchange - rages on.

In September, the LSE provoked the fury of shareholders by calling off a merger with Germany's Deutsche B�rse, in the face of a take-over bid from Sweden's OM Group.

UK mega-mergers

Vodafone Mannesmann - �112bn SmithKline Glaxo - �120bn Norwich Union CGU - �19bn

When the OM bid fell apart, the US Nasdaq exchange and Euronext, an alliance of the Paris, Brussels and Amsterdam exchanges, emerged as the two favourites to take over the London exchange.

The LSE continues to insist that it can stand alone.

Banking battles

The 'old economy' bore the brunt of the UK's merger frenzy.

Only December's �1.65bn sale of Freeserve, Britain's most popular internet service provider, to French rival Wannado bucked the trend.

Britain's banks and insurance companies, on the other hand, went through an unprecedented period of consolidation, as they faced up to increased competition from internet-based newcomers such as Egg and Smile, and depressed share prices.

At the start of the year, The Royal Bank of Scotland emerged triumphant in the bitter battle for NatWest bank.

The Bank of Scotland (BoS) saw its bid rejected and immediately became a take-over target in its own right.

An initial attempt to work out a deal with Abbey National, which had earlier swallowed Scottish Provident in a �2bn deal, ended in disarray, turning Abbey into a target for Lloyds TSB.

The Abbey board has rejected Lloyds TSB's �18.2bn bid and is re-doubling its efforts to strike a deal with BoS.

Deals that fell-through

EMI Time Warner British Airways KLM Carlton United News and Media London Stock Exchange Deutsche B�rse

Meanwhile, Barclays bought-out High Street rival Woolwich in a �4.5bn deal.

And Norwich Union joined forces with CGU in a �19bn deal to create Britain's largest insurance company CGNU.

Elsewhere, Thames Water was taken over by German utility giant RWE in a �4.3bn deal.

And oil giant BP Amoco went on a spending spree, swallowing up Burmah Castrol for �3bn and completing a �17.25bn take-over of US oil company Atlantic Richfield Co. (Arco).

In engineering, Smiths Industries took over its smaller rival TI Group in a �4.5bn deal.

Failed mergers

EMI's proposed �20bn link-up with Time Warner was among the mergers which failed to get off the ground in 2000.

The deal was derailed in October by EC competition watchdogs.

UK regulators torpedoed the proposed merger of ITV franchise-holders Carlton and United News and Media by insisting that United dispose of its Meridian franchise.

The move cleared the way for Granada to buy United's television interests for �1.95bn.

In September, British Airways and Dutch carrier KLM called off merger talks after failing to agree on a structure that would give BA control of the combined group.

British Telecom also attempted to extend its global reach by exploring a merger with US giant AT & T, eventually settling on $10bn global joint venture with the US firm.

It also paid 6.6bn (�4bn) euros, to take control of German telecoms group Viag Interkom, doubling its stake in the company to 45%.