The battle for the London Stock Exchange intensified yesterday when an Australian bank confirmed it was mulling over a takeover bid.
Macquarie Bank - which owns a stake in Birmingham Airport - said its " deliberations were at the most preliminary of stages" and any formal offer would be made through a consortium and probably in cash.
Its interest threatens to disrupt the plans of pan-European exchange Euronext, which is awaiting the final outcome of a Competition Commission inquiry into an earlier takeover approach.
Any offer would have to exceed 530p a share or the £1.35 billion already put forward by German suitor Deutsche Boerse, which was rejected last year by the LSE. Shareholder unrest later forced Deutsche Boerse to the sidelines.
Macquarie said it was "considering a number of potential acquisition opportunities which includes a possible formal approach being made to the London Stock Exchange".
The bank added: "If any bid were made, it would be as part of a consortium and if any such offer is made it is likely to be solely in cash."
The LSE is understood to be demanding at least 600p a share or £1.5 billion.
Macquarie typically focuses on property and infrastructure such as roads and airports, but the acquisition of the LSE would fit its model of buying a business with solid earnings streams and the potential to increase fees.
It has 24.125 per cent of Birmingham Airport, whose other owners are Irish group Aer Rianta with a similar holding, the seven West Midlands councils with 49 per cent and the Employees Shares Trust, 2.5 per cent.
Macquarie Airports also has interests in Sydney, Rome, Bristol, and Brussels airports.
A takeover of the LSE would broaden its footprint in Europe where the bank owns Isle of Wight ferry operator Wightlink and has a controlling stake in South East Water, which supplies water to approximately 1.5 million people in the UK.
Macquarie also has a 31 per cent interest in gas distribution firm Wales & West Utilities and is the sole owner of Energy Power Resources, which owns and manages the UK's largest portfolio of biomass fuelled renewable energy assets.
Last month, the Competition Commission said that a takeover of the LSE by Deutsche Boerse or Euronext would "substantially lessen competition".
It provisionally found that a merger with either would make it more difficult for other exchanges to compete with the LSE in the trading of UK equities.
A bid from Macquarie would not be hampered by monopoly worries. But further interest could be on the sidelines.
A weekend report suggested OM Gruppen was also mulling a bid. In October 2000, the LSE rejected a £1.06 billion offer from the Swedish exchange owner as inadequate.
"We're now certainly up to two potentially interested parties, Euronext and Macquarie," said Justin Bates, analyst at UK brokerage Numis Securities. "We have to assume a takeout value now above £6, given the way the business is trading and clearly it's a prized asset."
Macquarie is dubbed the " millionaires' factory" because of the big bonuses it pays.
"It's an unexpected development, but Macquarie are an innovative bank and you don't want to dismiss any potential bidder at a very early stage," said Richard Lacaille, chief investment officer at State Street Global Advisers, a shareholder in the LSE. Potential buyers of the LSE as members of consortia would be other stock exchanges, private equity firms or financial services firms, said JP Morgan analyst Brian Johnson.
"The reason why there are so many people lining up with basically takeover bids for it is clearly shareholders are dissatisfied with the way it is being run at the moment and perhaps that might create an opportunity," he said.
The LSE said it had not received a formal bid approach from Macquarie and that it remained confident about its prospects as an independent company.
Macquarie operates in more than 21 countries and has over 6,500 staff. It manages about A$91 billion (£38.7 billion) in assets worldwide, including motorways, utilities, aged care housing and property to media assets.