What Lumentum Taught Me About Stock Picking, Index Funds, and My Own Investing Persona
Every investor has a few ghosts in the portfolio; mine recently showed up in the form of Lumentum. By Benjamin Tan
I first bought Lumentum (LITE 0.00%↑) in March 2019 after reading a Barron’s article from late 2018 titled “Apple iPhone Supplier Lumentum Holdings Stock Looks Like a Buy.” At the time, the thesis seemed straightforward enough. Lumentum had exposure to Apple (AAPL 0.00%↑), optical components, and several promising technology trends. I took a position, watched it move, and later sold in 2019 and 2020 for a roughly 10% gain.
A gain is a gain, but recently, LITE 0.00%↑ became something much larger than the company I thought I owned. What I had viewed, partly through the lens of AAPL 0.00%↑ supply exposure, later became part of a much bigger story around optical networking, data centers, and AI infrastructure. LITE 0.00%↑went on without me, which still evokes a tinge of regret and a temptation to censure myself for lacking the conviction to hold.
Self-Reflection and Stock Picking
The LITE 0.00%↑ experience raises a more uncomfortable question: what exactly am I doing trying to pick stocks?
I could have put more of my capital into the S&P 500 or Nasdaq 100 and avoided a great deal of decision fatigue. No individual thesis to monitor. No earnings calls to interpret. No regret over selling too early. No need to ask whether I misunderstood the company, the cycle, the valuation, or myself.
That last part matters most.
Stock picking is usually framed as a contest against the index. Did you beat the S&P 500? Did you outperform the Nasdaq 100? Did your carefully researched stock justify the extra work, risk, and psychological noise?
Those are fair questions. They are also incomplete.
Stock picking is not just a performance exercise. It is a personality test with ticker symbols.
Some investors need simplicity. Some need control. Some need income. Some need intellectual engagement. Some need the thrill of hunting for the next great compounder, even if that thrill occasionally comes with a side order of regret. The right portfolio is not merely the one that looks best in a spreadsheet. It is the one that an investor can actually live with through changing markets, changing life stages, and changing emotional capacity.
Suit Yourself: A Portfolio to Match Evolving Personality
Suit Yourself Is Now Out!
After years of reflection and writing, my debut book, Suit Yourself: A Portfolio Strategy for Every Personality Type, is finally out, published through Koehler Books. This side passion project brings together my professional and personal journey across psychology, personal finance, and the many ways our identities shape how we invest.
That idea sits at the heart of my book, Suit Yourself: A Portfolio Strategy for Every Personality Type. The premise is simple: investing should reflect who you are. Not who you pretend to be on a finance podcast. Not who you are during a bull market. Who you actually are when life is busy, markets are noisy, and your attention is being pulled in 12 directions.
For me, that self-understanding is changing. I still enjoy individual stocks. I still believe there is value in studying companies deeply, like I recently did for Life Time Fitness (LTH 0.00%↑). Some of my best investments came from direct ownership, not passive exposure. But I am also becoming more comfortable with the idea that not every dollar needs to prove my ability to identify a winner.
Intellectualization and Self-Awareness
There was a time when I wanted more of my portfolio to reflect specific company-level judgment. I liked the process of studying businesses, forming theses, and owning the consequences. I still do. There is intellectual satisfaction in understanding why a company might be mispriced, why a market opportunity might be larger than consensus expects, or why a business model might compound longer than investors assume.
But there is also a cost. Individual stock picking requires attention. It requires conviction, but also flexibility. It requires the humility to change your mind without becoming erratic. It requires the patience to hold through volatility, but also the discipline to sell when the thesis breaks. That sounds elegant in theory. In practice, it can become a second job that pays in anxiety before it pays in returns.
And life changes. I am now balancing full-time clinical work, family life, investing, writing, and the ordinary logistics of being an adult. My portfolio no longer exists merely to express my curiosity. It has to support a broader life, and this is why my portfolio has been evolving. Recently, I have become more comfortable deploying capital into index funds, preferred securities, and fixed income ETFs. I have also been fortifying the income-producing side of my portfolio. My capital now has different jobs: some of it is there to compound, some of it is there to produce income, some of it is there to preserve flexibility, and some of it is there to reduce decision fatigue.
Intent Behind Each Investment
The lesson from LITE 0.00%↑ is not that I should never sell. The better lesson is that I need to know what kind of investment I am making before I make it.
If I buy a stock as a tactical trade, I should not be shocked when I sell it like a tactical trade. If I buy a company because I believe it can compound for years, then I need to give that thesis enough room to mature. If the original thesis changes, the question is not simply whether the old thesis worked. The question is whether a better, larger thesis has replaced it.
In Lumentum’s case, I owned one version of the story and missed the larger one. I saw enough to buy, but not enough to stay. That is frustrating, but it is also useful. Regret can be productive if it leads to clearer thinking. It becomes useless only when it turns into self-punishment or the lazy conclusion that every stock should have been held forever.
I also have to be careful not to self-select only the regrets. It is easy to remember LITE 0.00%↑ because it became painful in hindsight. It is easy to remember other stocks I sold too early. But that is not a complete audit. I also need to remember the stocks I sold correctly, the companies I avoided, and the winners I did hold through meaningful appreciation. A portfolio review based only on missed multibaggers is not wisdom. It is emotional cherry-picking.
Conclusion: Conviction, Humility, and Balance
Index funds are not just investment products. They are behavioral tools. They protect investors from needing to be right about everything. Passive investing is not intellectually inferior. In many ways, it is intellectually honest. It says: not every dollar needs to be clever, and not every position needs to prove my ability to outthink the market.
At the same time, I do not want to abandon individual stocks altogether. That would be inauthentic. I still enjoy studying companies, business models, and long-term themes. Active investing gives me intellectual engagement, and sometimes it gives me returns that justify the effort. The key is allocation.
A younger version of me may have viewed more indexing and income production as a reductive. I do not see it that way now. I see it as better alignment between portfolio structure and life stage. The goal is not to prove that I can pick every winner. The goal is to build and preserve wealth in a way I can actually sustain. That is the psychological side of investing. The spreadsheet matters, but so does the person using it.
LITE 0.00%↑ may have gone on without me. The lesson, at least, is still mine to keep.
My book, Suit Yourself: A Portfolio Strategy for Every Personality Type, blends Enneagram psychology, pop culture, and behavioral finance to offer a personalized roadmap to investing. It examines how personality biases unconsciously influence investing behaviors. Learn more at my author page or order the book on Amazon. Follow me on X.com (formerly Twitter) @ConsumeOwnTech and Yahoo Finance.
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