Virgin Atlantic is an attractive proposition for any major airline operating in and out of London's Heathrow Airport for one simple reason - its landing slots.
For Delta, the second-biggest airline in the United States and likely suitor for Singapore Airline's 49 per cent stake in Virgin, a deal would increase its access to Europe's busiest airport and boost its ability to capture transatlantic business traffic.
"What's most valuable about Virgin Atlantic is the slots it's got at Heathrow," said Paul Yong, the director of research at DBS Vickers Securities. "Any airline that's got significant operations into Europe would be interested."
The stake would also be of interest to airlines such as Etihad Airways and Emirates Airline, other Arabian Gulf carriers, Lufthansa and US airlines, said Mr Yong.
But it is Delta, a member of the SkyTeam global alliance, which includes Air France and 18 other airlines, that has made clear that it wants to expand at Heathrow.
Virgin is the second-largest carrier at Heathrow after British Airways, which is a member of the Oneworld alliance along with American Airlines. Both BA and American were recently given anti-trust law immunity by US authorities, allowing them to streamline their transatlantic operations.
"Delta now finds itself going up against the combination of American Airlines and British Airways," said George Hamlin,the president of the US-based Hamlin Transportation Consulting. "British Airways brings along a feed from other destinations - both Europe and intercontinental - at Heathrow. Delta is basically a dead end at this point."
Mr Hamlin said a tie-up with Delta could give Virgin access to hundreds of markets on a one-stop connecting basis in the US. For Delta, such a deal would help to plug a weakness in its global network versus key competitors and make it a strong player at Heathrow.
"London obviously is the premier market and Heathrow is by and large the market leader. It's the linchpin transatlantic market in terms of size and revenue, particularly premium traffic revenue," added Mr Hamlin.
It is unclear whether Sir Richard Branson would be willing to relinquish his majority stake in Virgin Atlantic, which he has held since founding the airline.