I made three costly mistakes this year.

All due to overthinking and personal bias. I did not respect my systems, and it cost me greatly. I'd estimate them to have cost me ~25% in YTD performance. Not a small miss.

Writing this helps me pinpoint the issue, identifying where and why things went wrong, and crystallizes the moment. This is how I learn, how I improve, how I ensure not to reproduce these mistakes in the second half of the year.

I already talked about my first mistake, but today is a great day to revisit it after a banger quarter and a new ATH.

$NBIS would now be a 7-bagger from my ealier average and a 9.5-bagger from my lowest purchase.

I no longer own the name.

I sold my position in February ~$85. I had the bias that declining margins from hyperscalers and increased CapEx would trigger more selling while the tech market was bearish.

I was wrong, but that wasn’t my mistake.

My mistake was to believe my bias to be more valuable than my system. If I had followed it, I would still be holding and sitting on ~750% return from my early 2025 purchases.

Sure, I realized my mistake, bought back at ~$110, and sold at ~$140 to concentrate on $SOI - which turned out to be a great move.

But breaking the system wasn't and the liquidity to buy $SOI should have come from other names - one we'll talk baout in my third mistake.

That was lesson one.

I haven’t broken my system on any core position since. I hold a thesis and price action; as long as neither breaks, I hold my stock.

The involved both $LUNR and $RKLB. I wrote a clear, detailed write-up on both explaining why I was buying them, justifying the obvious bull market in space, and why those two would be winners.

The plan was clear from thesis to execution. Since these positions were bought at a high valuation, they came with a stop loss to protect my capital - which was on margin.

But last week, after $FLY and $BKSY earnings and the red reactions, I decided to reduce my position in both as they were trading ~2% above my stop loss around my entry price.

My plan was crystal clear and the risk was controlled. But I chose to reduce it because... something "seemed" wrong? I am not even sure why.

Nevertheless, I did.

$RKLB went on to trigger my profit-taking order at $99, and $LUNR is still running, now up 50% since entry. What should have been two 40%+ trades turned out to be less than hald of it, for no reason.

I had a trading plan. Controlled risk. And I chose to not trust myself.

That was lesson two.

$TMDX has been the most important lesson for this year. I said I closed $NBIS to buy $SOI, that was as I refused to close $TMDX despites no performance, no volume, no narrative.

I closed a winner to hold a favorite. Closing this position was harder to me than closing a winner with tailwinds and perfect execution.

The stock turned out to be a loser and fell a sharp 45% since I closed my position. But I should have closed it sooner.

If a stock doesn't respect your buying condictions anymore, you have no reasons to hold it. Markets are too unforgiving to waste capital on a name outside of your system, just because you like it.

That was lesson three.

The problem with those three lessons is that fixing them is pretty hard, for a simple reason.

They are all psychological.

The first was about fear, the second was about doubt and the third was about attachement.

The only way to get rid of them is either to print in your brain that the feeling of losing is worst that the feeling of selling a name you love or holding a name you doubt on despites you clear plan.

Or to build systems. Hacks that will force you not to overthink a position or hold onto it too long. Automations or actions to avoid being in this situation.

I will have to think more about the solutions, but the mistakes and symptoms are clear, and that is already a massive step to improving.

Our investing is only as good as our poorest decision.