Answer: with any existing customer who is a resident of Illinois and is on vacation anywhere in the United States.
Step-by-step explanation:
A broker-dealer is an economic agent that purchases and also sells securities for either its own account or transacts on behalf of its customers.
A broker-dealer that is registered in Illinois and that is not registered in any other State may effect transactions in securities with any existing customer who is a resident of Illinois and is on vacation anywhere in the United States.