AST SpaceMobile (ASTS -2.02%) stock opened dramatically higher on Monday morning, up 7.3% over the weekend after an early-morning press release announcing the company will form a new satellite communications business with European partner Vodafone (VOD 0.14%).

Investors already seem to be having second thoughts about this news, however. As of 10:05 a.m. ET, AST stock has given up all its gains and is now trading in the red -- down 0.5%.

AST and Vodafone: Better together?

AST says the goal of its joint venture with Vodafone is "to provide 100% geographic coverage in every part of Europe" from AST's BlueBird satellites in orbit. The new business, currently named SatCo, will "exclusively distribute AST SpaceMobile's satellite services to European" telecommunications providers. SatCo will also "build and run a network of ground stations to provide backhaul services" in Europe, integrating terrestrial and satellite communications.

Not only will Vodafone customers be able to "stay connected, wherever they are," says Vodafone, but through the new joint venture, "other European mobile operators" will be able to participate as well.

Is this good or bad news for AST SpaceMobile?

Vodafone and AST gave no further details on their partnership -- which seems great at first blush and probably explains why AST stock opened higher this morning. Still, there must be something in this news that's spooking investors and causing them to sell off their AST shares on further reflection.

What might that be?

The answer may lie in the structure of the partnership. If AST were providing satellite communications services directly to telecoms, one at a time, it would presumably collect payment from those customers directly as well. The alliance with Vodafone, in contrast, seems to run payments through the JV. Presumably, such a structure also splits payments (i.e., revenue and profit) between AST and Vodafone -- diminishing AST's potential revenue and profit.

Granted, AST's also gaining a powerful partner to help market its services and win customers. Still, investors now seem to be viewing the structure as a net negative for AST SpaceMobile stock.