See Rev. Rul. 2008-5 (https://www.irs.gov/pub/irs-irbs/irb08-03.pdf) which provides that "if an individual sells stock or securities for a loss and causes his or her IRA or Roth IRA to purchase substantially identical stock or securities within a specified period [30 days before or after the sale], the loss on the sale of the stock or securities is disallowed under section 1091 of the Code, and the individual’s basis in the IRA or Roth IRA is not increased by virtue of section 1091(d)."
