ETFs trade at NAV because AP, intraday
  Mutual funds trade at NAV directly, only once a day


  MUTUAL FUND PROBLEMS
  1. Liquidity and redemption issues
  2. Higher costs
  3. Cash drag


  ETF PROBLEMS
  VII. Exploiting Section 852(b)(6): Heartbeat Trades and Capital Structure Arbitrage
  A. Heartbeat Trades
  B. Custom Baskets
  C. AP Motivation for Heartbeat Trades
  D. The Tax Lollapalooza: Heartbeat Trades and Vanguard’s Capital Structure Arbitrage








Sources
  https://businesslawreview.uchicago.edu/print-archive/unplugging-heartbeat-trades-and-reforming-taxation-etfs