Because their share price is largely built on the value of $US...

Because their share price is largely built on the value of $US cash backing and revenues and the $US has been heading south.

Their various joint targets seem a long way from producing more cash than they absorb and much of the cash backing will be spent in the process for unknown success and return at this stage.

There might be an acceptable risk/reward case for AAH shares, but it is impossible to know at what point the market will see it as compelling.