If I am correct - and sometimes I am - When the paperwork for the corporate action is submitted, the ticker moves over to a temporary ticker, which will be BLTA+ an extension. That happens overnight. The USGL ticker is set up and established through the networks. The trading moves to the USGL ticker after 3 or four days in an overnight process.

Need to keep in mind that trading is not the only system impacted. Custodial systems, trade matching engines, trade confirmation engines and other reference/records systems need to transfer data and other elements. Unfortunately, its not and clean cut as changing 4 letters. Plus these systems are not just SEC systems - Fidelity and all other companies systems all need revision. Partly why it is handled through a corporate action, gives time to filter through the market... Its actually more common than you think....