The only thing worse than a double negative is a double double negative

Before

Whether or not Adviser may acquire, or not acquire, securities or property for itself or for any other client will not be considered in determining the advisability of acquiring or not acquiring similar securities or property for the portfolio account of any client.

(43 confusing words)

Before, with commentary

Whether or not Adviser may acquire, or not acquire, securities or property for itself or for any other client will not be considered in determining the advisability of acquiring or not acquiring similar securities or property for the portfolio account of any client. [Can you get your head around that?]

After

We will decide which securities or property to acquire for your account without regard to whether we can acquire similar securities or property for other clients or for our own account.

(clarity in 31 words)