since you say you reported all you can write a letter trying to explain what you did, but the IRS most likely would like a corrected 8949 - break out the trades. probably some are type A (short-term) or D (long-term) - cost basis reported to IRS and others may be type B (short-term) cost basis not reported to IRS. the STC shares are short-term while other shares you sold might be long-term so putting the STC sales together with other shares sold might result in you having underreported your taxes though your taxable income is correct. long-term shares get a special tax rate short-term do not
this is what the IRS says if you disagree
If you disagree, complete and return the response form. Provide a signed statement explaining why you disagree and supply any documentation to support your statement.
you'll have to see if your taxes change when you separate the STC shares - so a corrected 8949, schedule D and 1040-X may be required.
