$! does not return PID of background process?

Using the following example:

$ sleep 10000 &
[1] 0xfff427e1
-776223
$ ps | grep sleep
0xFFF4E619 32C sleep 10000
0xFFF4AF79 32C sleep 10000


$! is NOT returning the PID for the background process.

This is not a MKS bug, Win95 violates POSIX, it is returning a negative pid, which is illegal in the POSIX.1 specification.

On the other hand, if this is occurring in a subshell, it is attributable to the fact that Windows does not have an overlaying exec() call.