A Section 351 exchange lets an investor contribute appreciated securities to a newly launched ETF without recognizing gains at contribution. The explorer below tracks the funds using it, live from the 351.tax data feed. For the mechanics and the limits, start with Managing concentrated stock by seeding an ETF.
Section 351 ETF explorer
ETFs seeded in-kind under Section 351, tracked live: funds launched, current AUM, deferred gains, and the pipeline.