Boris Johnson joins lobbying for UK chip designer Arm to list in London

Boris Johnson has joined the lobbying effort to convince the British-based chip designer Arm to float in London, as the government fears the damage of losing out to New York in the battle to attract high-profile tech companies looking to list.

Johnson has joined the lobbying efforts already under way by London Stock Exchange executives and a number of government departments and senior officials, writing a letter to Softbank executives, according to the Financial Times.

Analysts are estimating that Arm would float with a market value of $30bn to $40bn, which would make it the largest tech company on the London Stock Exchange, more than twice the size of the current leader, Ocado. At that scale, Arm would also rank between the 19th and 24th largest listed company in the UK.

Last year new rules were introduced to try to make London more attractive to tech companies, including allowing dual share class structures, which give founders more control after they float a business, and reducing the amount of shares required to be offered to the public to 10%.