They lost millions of client funds due to their order book engine, yet there is no mention here, and no comment made by Kraken about their trading engine blocking orders for regular users while still accepting some API orders. I'd wager 10000USD that Kraken employees were submitting sell orders while everyone else was locked out of the order books when we fell from 8800yuan.

https://www.reddit.com/r/BitcoinMarkets/comments/5pbpfu/reminder_kraken_is_a_scam_exchange/