USBE and VSE merger

[slicky]

I own shares in USBE. Couple of days ago, VSE announced that it is buying USBE for $8.62 a share. And, USBE shareholders will receive .81 share of VSE for each USBE stock.

Today USBE's share closed at $9.07. How does this work? Why do people are now paying more for USBE stock? Can you still buy USBE shares and get VSE shares once merger is complete?

Thanks in advance for clearing up my confusion....