Yes you do.
IF you don't the IRS is notified of the transaction thru electronic filings from the brokers too, and when their computers start doing detailed comparisons, they then tend to send letters to taxpayers later assessing a tax on all of the proceeds, not just the gain. So they expect you to report everything. They get so much data early in the year, that the computers only do cursory comparisons of all the data sent in...the detailed examinations start later.
____________*Answers are correct to the best of my knowledge when posted, but should not be considered to be legal or official tax advice.*
