An American firm is gatecrashing a £1bn agreed takeover of Spirent Communications, the cybersecurity specialist, within the newest instance of a bidding struggle breaking out for a London-listed firm.

Sky News has learnt that Keysight Technologies, which is publicly traded in New York, is getting ready to launch a proper provide for Spirent value roughly 200p-a-share.

That would worth the FTSE 250 goal at about £1.15bn.

Keysight's bid will trump a 175p-a-share bid unveiled final month by Viavi Solutions, a US-based expertise firm.

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Viavi's proposal was backed by a $400m monetary dedication from Silver Lake Partners, the non-public fairness group whose investments embrace the mum or dad firm of Manchester City Football Club.

One institutional investor mentioned they anticipated the upper provide to steer Spirent's board to modify its advice from Viavi to Keysight.

Spirent, whose roots date again to 1936, checks 5G and WiFi networks for shoppers predominantly within the telecoms sector.

Headquartered in Crawley, it employs about 1,500 individuals.

It grew to become often known as Spirent, having beforehand been known as Bowthorpe, in 2000.

The rising bidding struggle between two American corporations for a London-listed expertise supplier will once more increase questions on whether or not the UK fairness markets are mispricing profitable companies with substantial development prospects.

The UK's sluggish financial system and a weaker pound have mixed to make British corporations significantly enticing to US-based predators.

The Viavi provide was pitched at a premium of greater than 60% to Spirent's share worth of 108.4p on the day earlier than its announcement.

That would imply Keysight's bid can be value roughly 90% greater than the goal's prevailing share worth - a steep premium within the context of London inventory market takeovers in current a long time.

Some institutional shareholders in Spirent had indicated that whereas they might vote in favour of the Viavi provide, they believed it was opportunistic and left the door ajar for a rival bidder.

It was unclear on Wednesday whether or not Viavi can be ready to return with an elevated provide within the wake of Keysight's method.

So far this 12 months, corporations together with Wincanton, the logistics specialist, have agreed takeovers by abroad suitors, whereas this week New York-listed International Paper confirmed a Sky News report that it was getting ready to supply greater than £5bn to purchase the FTSE 100 paper and packaging firm DS Smith.

Other London-listed corporations which have attracted curiosity embrace Currys and Direct Line Group, though their potential bidders subsequently walked away.

Bankers at Centerview Partners and Evercore are understood to be advising Keysight, whereas Spirent is being suggested by Rothschild, UBS and Jefferies.

Viavi is being suggested by Qatalyst Partners and Wells Fargo.

Spirent was contacted for touch upon Wednesday night, whereas Keysight couldn't be reached for remark.