US-based private equity group KKR is the group behind a possible takeover bid for Alliance Boots, BBC business editor Robert Peston has learned.
Private equity bidders have targeted the firm, speculation suggests
Boots shares soared more than 18% after it said it had received a "preliminary and highly conditional" approach.
Mr Peston added the fact that one of Boots' key investors was working with KKR on the offer "massively increased the likelihood" of it going through.
Traders suggest any bid for Boots could be as high as £10 ($19.30) per share.
According to Mr Peston, Monaco-based Italian billionaire Stephano Pessina - who controls a 15% stake in Boots - is collaborating with KKR on the offer.
He added that KKR/Pessina would not have to persuade too many investors to agree to the deal as more than half of the health and beauty retailer's shares in the hands of relatively few investment institutions.
"One bunch of brainy people who presumably are feeling a little silly tonight are investment banks' sell-side analysts, since almost all of them rated Boots's shares as a 'sell'.," Mr Peston said.
"Their bearishness seems to have given Pessina his opportunity to offer just under £10bn for a business with formidable cash-generating capacity and a great opportunity to expand around the world.
"Looks as though another great British business may soon be in overseas hands," he added.
KKR recently hit the headlines as it emerged it is considering a bid for supermarket group Sainsbury's.
So far, Boots has declined to name its potential suitor.
However, our business editor says it is not clear whether KKR's interest in Boots would have any implications for the Sainsbury deal.
KKR is the world's biggest private equity firm and was recently part of a consortium involved in the $45bn (£22.9bn) buyout of US utility TXU Energy - the world's biggest private equity deal.
Alliance Boots was formed last year by the £7bn merger of Boots, whose retail arm is based in Nottingham, and chemist group Alliance Unichem.
The tie-up created one of Europe's largest drugs, beauty and healthcare groups, with sales of more than £13bn. Its retail arm is based in Nottingham.
Shares in the firm closed 115p, or 14.11%, higher at 930p on the London market.