Update

after writing the below article: Kraken replied and said :

“I apologize, but there isn't anything we can do for you here, unfortunately. Let us know if you have any other questions.”
The full reply is in the comments below.

end of update

Below is the original post I made on 6th November

Today I placed two small deferred "sell", "limited", orders on Kraken. Something went terribly wrong. Both trades had terrible executions. One was traded at around $90 below the market and the second order, 2 hours later, at about $125 below the market.

The instructions were identical, except for the time they were to be placed on the market (the "start" time). Both instructions were to sell 0.3 bitcoin at $7'450 or better. ("Limit" orders").

The whole point of deferring an order like this is to spread a sale throughout the day, so you get an average of the day's prices, but no worse than your limit. You don't need to stay in front of your computer to place the orders. They will be dropped in the market at the times you specify.

I set the time for my two orders to 13:00 and 15:00 (both based on the Kraken time). Those are the times the orders are automatically placed on the market. They can't be placed before the start time.

I set the limit for each of the sales at $7'450 which was slightly higher than the market price at the time I was entering the order.

You can set the time when an order is placed on the market using the "Start function, as shown in the pictures below:

The whole point of a "limited" order is that if it is capable of being executed at the start time, you should get the BETTER of the "limit" price, or the "market" price. In both cases, I got the WORSE of the two. I am not talking about a few cents. I am talking about a difference of close to $100. This can't be accounted for by the spread between bid and ask. At the start time the bid-ask spread was minimal.

Below you can see the two price feeds of executed trades at the times of Execution. Here is the price feed of the first execution. The start time was set to 13:00, which corresponds to the trade time. You can see my trade highlighted. It was executed at my limit of $7'450 - which was $90 below the market:

Here is the second trade that I set to be placed on the market at 3pm. This time it was also executed at my limit price of $7450, instead of the market price. The execution price was around $125 below the quoted bid-ask at the time.

Below you see all the trades and times. The red arrows are "sell" orders at the "bid" price and the green arrows are "buys" at the ask price. As you can see my trade was a "sale", except it was executed nearly $125 BELOW the bid price.

Here are some screenshots of the bar chart I took immediately after the first bad execution.

I don't know why my sale price, (twice in a row), was at the "limit" price, instead of the much higher "bid" market price.

I would speculate that it is most likely a software bug.

I put in a support ticket to Kraken to see what they will say. I will you know.

I received an automated email response as follows:

"Thanks for contacting Kraken Support. Your request has been received. We'll reply to your ticket as soon as possible, but in some cases it can take several days if we experience a heavy volume of requests. We have site content that answers many of the most common support questions. Please take a moment to visit the pages below and see if your question is answered there."

If you use Kraken, I would avoid using the "Start time" feature until this problem is resolved.

I would like to ask Kraken: "Who took the other side of my trade?" "What would have happened if my limit had been 1 cent, or zero?"