The closing auction accounts for a striking 7.5% of daily volume in 2018, up from 3.1% in 2010. The growth of indexing and ETFs shifts trading towards the close and distorts closing prices: they often deviate from closing quote midpoints, but the deviations revert by half shortly after the close and fully overnight. As volume migrates towards the close, liquidity at the open deteriorates.
See also:
TPR (Jan 12, 2023) - The ICT Power of 3: Accumulation - Manipulation - Distribution (AMD).