If you sell a stock for a loss and purchase substantially identical stock either 30 days before, 30 days after, or on the day of the sale, you've executed a wash sale.
Tradesk is required to report wash sales on a same account same, security level. Wash sales not reported by Tradesk due to different accounts and being a similar security are the responsibility of the taxpayer. The IRS prohibits taxpayers from claiming losses on these transactions from wash sales for tax purposes. The loss is added into the cost basis of the shares you replaced your original stock with. The holding period of the investment you sold is also added to the holding period of the new investment. For details, refer to the Wash Sales section.
You can find your total wash sales for the year in Box 1G on your 1099 tax document.