Your client gets a bunch of shares in OpenTable as part of a venture capital investment distribution. The shares were delivered to Credit Suisse. But your client doesn't want an account set up there - he has his primary account with Goldman Sachs. So he wants the shares wired to his GS account whenever there is a venture capital distribution. Instead of having to grind through endless paperwork each time there is another distribution, he sets up an ACAT once and is done. The ACAT is respected by the brokerage community who comply with the processes of delivering customer assets like cash and stock and Christmas nut cakes to the core or main target account.