The boss of Salesforce. com has ruled out his company as a bidder for Twitter, all but bringing an end to attempts to find a buyer for the struggling internet company.

The US cloud software company had been left as the most likely bidder last week after other potential acquirers, including Google and Walt Disney, decided not to pursue a deal.

"In this case we've walked away. It wasn't the right fit for us," Marc Benioff, chief executive of Salesforce, said in an interview with the FT. Twitter's shares tumbled more than 6 per cent on the news.

Salesforce had been the only serious contender left in the race after Twitter opened itself to takeover offers, two people briefed on the sale process said. However, Twitter’s advisers are still seeking other potential bidders, those people added.

The sale process is virtually dead, said a person close to Twitter’s senior management.

Twitter's management could still explore the option of a buyout backed by wealthy investors or an activist could try to unseat chief executive Jack Dorsey and force the board back to the negotiating table. But both seem increasingly unlikely. – Copyright The Financial Times Limited 2016