According to CNBC, the IRS and Treasury Department have warned on two ETF strategies that can sharply reduce wealthy investors' tax bills, including certain Section 351 ETF conversions and so-called no dividend strategies, and asked for public comments by Oct. 28. The IRS said future guidance on these tax-aware funds may apply prospectively or retroactively, while tax professionals said investors should be prepared to justify the purpose of the strategies and keep documentation in order. The notice also singled out novel investment fund strategies that may produce results inconsistent with the tax rules, including approaches that use straddles to generate capital gains and ordinary losses from offsetting positions.