Andy, $68,$ has a gross estate currently valued at $$2,500,000$ that consists primarily of highly appreciated growth securities$.$ Within the last six months, Andy transferred $$500,000$ worth of these securities to his wife, Harriet. His cost in these securities was $$200,000.$ Harriet recently died. The fair market value of the transferred securities at the time of her death was $$500,000.$ The securities passed to Andy under the terms of Harriet's will.

Which one of the following is an income tax implication of the transfer of stock?