Uncertainty in the OTC markets quickly drove spreads to 5% on March 12, before they exceeded 10% on certain platforms the next day
Source: https://cointelegraph.com/news/otc-spreads-exceeded-10-amid-bitcoins-violent-march-crash
OTC Spreads Exceeded 10% Amid Bitcoin’s Violent March Crash
April 8, 2020
CoinTelegraph