Anyone who has been trading for a while will probably relate to this topic...

If there is one type of loss that can drive me crazy is an operational loss, a stupid mistake just because I didn't pay enough attention to details, didn't take one second to look before execution

I don't mind losing money over a trade that backfired, a strategy that my model signaled and went wrong due to market dynamic. These losses I can backtest, analyze, and learn from, so the loss has educational value. When you lose money over operational loss there is no lesson

other than "don't be stupid, pay enough attention to details, do better backoffice work". This can literally make me bang my head against the wall 1000s times. I will give my top three operational mistakes of my career so far (hoping there will be no others)

1. double fat-finger - in a middle of a NFP chaos put a T/P order in NZD/CAD to sell 4mm . mistakenly had the wrong big figure and instead of 4mm did 400mm... make long story short - realized in selling at the market bid (0.3% below mid) , and found out after my order was 150mm

done... tried to cover, market was wide... finished this fiasco with a month lost on the first Friday of the month...

2. never leave your computer opened - Friday evening, family dinner, my older daughter (she was 3yrs old back then) went to my computer to watch youtube,

but one of my eFX platforms was opened, and she clicked on few tiles... apparently she trades about 50mm in Asia ccys NDFs (in US timezone)... luckily was a move in my way by time I found that so had to take a small loss.. If my firm would have known that back than I would

probably be gone in a heartbeat...

3. Always make sure your cashflow is closed - Dec 2015, closed option strategy in ZAR (most volatile EMFX back then). Had a nice profit, so was only make sense to close.. unfortunately didn't notice that my position in ZAR is not converted to

USD (so I was about $1mm worth in ZAR terms)... this was quite unfortunate, as the Prime Minister fired the Finance Minister, which made the ZAR sink 10%. by the time I found that I lost about $100k on a stupid back-office mistake. Nothing worse than losing 100k in Dec

All these mistakes were avoidable, and this is what makes them worse than just trading mistakes...

Feel free to share your examples of avoidable stupid mistakes..