Exchange hacks & DDoS attacks are not the only risks centralized exchange users face when trading cryptocurrencies.
A few weeks ago, Kraken exchange experienced extreme price spikes on the eth/btc & btc/eur markets.
During high load, on May 24th, Kraken's API briefly returned a price of 7.847btc per eth and a 24h btc volume of around 965,081btc, an improbable price & volume 100 times increase!
Some chart observers believed those spikes were just display glitches and thought no trades actually went through.
This is not what Reddit users CarryTrd & I, Sameux (respectively affected by x10 & x100 price spikes) experienced.
CarryTrd had an order fulfilled at 0.795btc per eth which caused a 4.9btc debt (around $13,000 at June 13th 2017 price) showing on his Kraken account.
I, had orders fulfilled at more than 7.86btc per eth triggering exchange automated "sell/liquidation market" orders leading to a loss of 140eth (around $53,000 at June 13th 2017 price).
Kraken exchange staff did not yet state whether this software issue is fixed or not.
They did not yet reply to my support tickets, almost 3 weeks after the incident.
Other Kraken users should consider this an additional risk as we may never be compensated.
Any user might still be randomly affected by this unreliable trade engine, especially during high volume times.
But there's some light at the end of the tunnel: more mature & open trade engines might arise with peer to peer exchanges like NVO or OmiseGO.
Be careful trading at Kraken!