TMDX
TransMedics Group, Inc. Common Stock
stock NASDAQ

In the context of the portfolio as it exists today, I’ve only made a couple of changes. Sorry if this is TMI.
First was Natera in for Meta in April. Took a \~£70 loss on Meta at the time. That decision was primarily driven by a couple of factors. I had been struggling to reconcile holding both Meta and Google given that they share a lot of similarities in terms of their risks and exposure to the AI capex cycle. This is relevant because I run a concentrated portfolio, and I try and avoid duplicating exposure where possible unless there’s clear justification. Moreover, Natera had receded from its highs and was around $200 a share. I’d already done enough research on NTRA to know that it was a stock I wanted to own. So, I decided that, in the round, it would better balance the portfolio if I made that swap.
I would add that the NTRA/META change was done before I had really firmed up my rules around selling positions. That isn’t to say that I wouldn’t have made the change anyway, it’s just that now I really hold myself to account on the reasons I own a stock int he first place. Thesis deterioration is the main thing I focus on, and I assess that both qualitatively through earnings and qualitatively by bouncing my own thoughts around with the help of Claude, who knows the rules I’ve implemented. In the past, I would make changes to the stocks I owned on a far more regular basis, and for reasons that were unclear in retrospect and based on impulse. It works well, because it also relies on me having clarity of thesis on prospective new additions too, not just on the holding that I might be considering selling.
The more recent change was Transmedics for ServiceTitan, which I executed just after my Q2 cycle closed. I won’t go into the thesis around TTAN (if you’re interested there’s a separate post about that on my page) but this change came after I’d tightened my aforementioned rules. So, prior to even contemplating removing TMDX I already had clarity of thesis on TTAN and knew it was a stock I wanted to own in the right circumstances.
Anyway, TMDX had already been in ‘probation’ from Q1 due to reasons that are myriad and complex. All you need to know is that the business was in flux to say the least. I had originally bought TMDX because it was clear that they had a moat regarding their warm profusion transplant technology. They also had a software layer that accompanies that tech.
One of the central characteristics of my portfolio is that I like companies that have proprietary hardware that they can enhance with software.
Whilst this was true with TMDX, it wasn’t clear that it actually made their moat stronger. It was more of a ‘feature’ than anything else, and it didn’t attract other things that make software attractive from an investment perspective (subscriptions, recurring revenue).
The catalyst for actually making the change, though, was TTAN’s 30% drop after their earnings. I looked into the reasons why the drop had happened, and was comfortable that a) management knows what they’re doing (they’re founder led, helps), and b) the drop was exaggerated.
It was in the context of that opportunity that I really started to question TMDX, because there was an opportunity with TTAN which I thought was very attractive and had more manageable downside protection at the price it was at at that time. The situation with TMDX hadn’t gotten any worse since I’d put them in probation after Q1, but the situation with TTAN prompted me to really interrogate why I owned the business. Ultimately, I made the call to swap.
I hope that answers your question. I’ve answered elsewhere about how I identify stocks in the first place if you want a specific answer on that 👍
… this would’ve been a lot easier to write with AI 🤣

In the context of the portfolio as it exists today, I’ve only made a couple of changes. Sorry if this is TMI.
First was Natera in for Meta in April. Took a \~£70 loss on Meta at the time. That decision was primarily driven by a couple of factors. I had been struggling to reconcile holding both Meta and Google given that they share a lot of similarities in terms of their risks and exposure to the AI capex cycle. This is relevant because I run a concentrated portfolio, and I try and avoid duplicating exposure where possible unless there’s clear justification. Moreover, Natera had receded from its highs and was around $200 a share. I’d already done enough research on NTRA to know that it was a stock I wanted to own. So, I decided that, in the round, it would better balance the portfolio if I made that swap.
I would add that the NTRA/META change was done before I had really firmed up my rules around selling positions. That isn’t to say that I wouldn’t have made the change anyway, it’s just that now I really hold myself to account on the reasons I own a stock int he first place. Thesis deterioration is the main thing I focus on, and I assess that both qualitatively through earnings and qualitatively by bouncing my own thoughts around with the help of Claude, who knows the rules I’ve implemented. In the past, I would make changes to the stocks I owned on a far more regular basis, and for reasons that were unclear in retrospect and based on impulse. It works well, because it also relies on me having clarity of thesis on prospective new additions too, not just on the holding that I might be considering selling.
The more recent change was Transmedics for ServiceTitan, which I executed just after my Q2 cycle closed. I won’t go into the thesis around TTAN (if you’re interested there’s a separate post about that on my page) but this change came after I’d tightened my aforementioned rules. So, prior to even contemplating removing TMDX I already had clarity of thesis on TTAN and knew it was a stock I wanted to own in the right circumstances.
Anyway, TMDX had already been in ‘probation’ from Q1 due to reasons that are myriad and complex. All you need to know is that the business was in flux to say the least. I had originally bought TMDX because it was clear that they had a moat regarding their warm profusion transplant technology. They also had a software layer that accompanies that tech.
One of the central characteristics of my portfolio is that I like companies that have proprietary hardware that they can enhance with software.
Whilst this was true with TMDX, it wasn’t clear that it actually made their moat stronger. It was more of a ‘feature’ than anything else, and it didn’t attract other things that make software attractive from an investment perspective (subscriptions, recurring revenue).
The catalyst for actually making the change, though, was TTAN’s 30% drop after their earnings. I looked into the reasons why the drop had happened, and was comfortable that a) management knows what they’re doing (they’re founder led, helps), and b) the drop was exaggerated.
It was in the context of that opportunity that I really started to question TMDX, because there was an opportunity with TTAN which I thought was very attractive and had more manageable downside protection at the price it was at at that time. The situation with TMDX hadn’t gotten any worse since I’d put them in probation after Q1, but the situation with TTAN prompted me to really interrogate why I owned the business. Ultimately, I made the call to swap.
I hope that answers your question. I’ve answered elsewhere about how I identify stocks in the first place if you want a specific answer on that 👍
… this would’ve been a lot easier to write with AI 🤣