Several ETFs hold significant positions in Thermo Fisher Scientific, but the weighting varies dramatically—from less than 1% to over 3% in some concentrated funds. What else is in the fund matters just as much as the TMO allocation itself, because you're buying exposure to hundreds of other holdings alongside it. Understanding which ETFs give you the most direct exposure to Thermo Fisher, and whether that exposure actually moves the needle in your portfolio, helps you decide if you're better off owning the stock outright or getting diversified access through a fund.
Key takeaways
- The largest ETFs holding Thermo Fisher typically allocate between 0.5% and 3% of their portfolios to TMO, meaning a $10,000 investment might give you only $50 to $300 of actual exposure to the stock
- Healthcare sector ETFs tend to have higher TMO weightings than broad market index funds, but they also concentrate your risk in a single industry
- Total portfolio impact depends on fund size—a 2% weighting in a $5 billion fund represents far more institutional buying power than 2% in a $100 million fund
- Owning TMO directly gives you full exposure without dilution, but ETFs provide instant diversification and can reduce single-stock risk
Which ETFs have the highest Thermo Fisher weightings?
Healthcare sector ETFs typically hold the largest positions in Thermo Fisher relative to their total assets. These funds focus specifically on companies in pharmaceuticals, biotech, medical devices, and life sciences, so they naturally overweight major players like TMO. Broad market index funds also hold Thermo Fisher, but the allocation is usually smaller because they spread capital across every sector of the economy.
When you look at ETF holdings data, you'll see two key metrics: the percentage of the fund allocated to TMO, and the total dollar value of that position. A fund with 2% allocated to Thermo Fisher and $5 billion in assets holds $100 million worth of TMO shares. A smaller fund with the same 2% weighting but only $200 million in assets holds just $4 million. The percentage tells you how concentrated the bet is, but the dollar amount tells you how much institutional demand that fund creates for the stock.
Sector-specific ETFs often carry weightings between 1.5% and 3.5% for a single large-cap holding like Thermo Fisher. Broad market funds that track the S&P 500 or total stock market indexes usually allocate between 0.3% and 0.8%. Equal-weight funds treat every holding the same regardless of market cap, so they might hold TMO at around 0.2% in a 500-stock portfolio.
ETF weighting: The percentage of a fund's total assets allocated to a specific stock. A 2% weighting means that if the fund has $1 billion in assets, $20 million is invested in that stock. Higher weightings amplify the impact of that stock's performance on the overall fund return.
How much actual exposure do you get through an ETF?
If you invest $10,000 in an ETF that holds Thermo Fisher at a 1.5% weighting, you're getting $150 of indirect exposure to TMO. The rest of your capital is spread across the other holdings in the fund. That means if Thermo Fisher's stock rises 10%, your $150 exposure grows to $165—a $15 gain on your $10,000 investment, or 0.15%. The other 98.5% of your portfolio is subject to the performance of the remaining holdings.
This dilution effect is exactly what diversification is designed to do. You reduce the impact of any single stock's volatility on your overall returns. But it also means that if you specifically want exposure to Thermo Fisher's growth, an ETF with a low weighting won't deliver much of it. You'd need to invest significantly more capital to get meaningful TMO exposure through a fund with a 1% allocation than you would by buying the stock directly.
Healthcare ETFs with higher Thermo Fisher weightings give you more concentrated exposure. A 3% allocation in the same $10,000 investment scenario means $300 of TMO exposure. If TMO rises 10%, you gain $30, or 0.3% on your total investment. That's double the impact of the 1.5% weighting, but still a fraction of what you'd capture by owning the stock outright.
What else is in the fund, and why does it matter?
The other holdings in an ETF determine whether the fund aligns with your broader investment goals. A healthcare-focused ETF holding Thermo Fisher also holds pharmaceutical companies, biotech startups, medical device manufacturers, and health insurers. If the sector underperforms, your entire position suffers regardless of how well TMO does individually. A broad market fund spreads risk across technology, financials, consumer goods, and energy, but it also dilutes your exposure to any single sector's growth.
You should evaluate whether you want the additional exposure that comes bundled with the ETF. If you're bullish on life sciences and diagnostics broadly, a healthcare ETF makes sense. If you believe Thermo Fisher will outperform its peers, direct stock ownership might be more efficient. If you want diversified equity exposure and just happen to like TMO as part of a balanced portfolio, a total market index fund works fine.
Fund composition also affects risk. An ETF holding 50 stocks concentrates risk more than one holding 500. An equal-weight fund treats a $10 billion company the same as a $500 billion company, which can lead to higher volatility. A market-cap-weighted fund gives larger companies bigger allocations, which tends to smooth returns but also means smaller positions in mid-caps like some of TMO's competitors.
Should you own Thermo Fisher directly or through an ETF?
Direct ownership makes sense if you want full exposure to Thermo Fisher's performance without dilution. If you invest $10,000 directly in TMO and the stock rises 10%, you gain $1,000. If you invest the same amount in an ETF with a 2% TMO weighting and the stock rises 10%, you gain $20 from that position plus whatever the other 98% of the fund does. The trade-off is that owning individual stocks requires more active management, research, and tolerance for single-stock volatility.
ETFs work better if you want diversification without the effort of building a portfolio yourself. You get instant exposure to dozens or hundreds of companies, which reduces the risk that one earnings miss or management misstep wipes out a significant portion of your capital. You also avoid the need to monitor individual companies, rebalance manually, or worry about sector concentration. The cost is lower return potential if your chosen stock outperforms the rest of the basket.
Some investors split the difference. They hold a core position in a diversified ETF and layer in individual stock positions where they have high conviction. This approach gives you broad market exposure with the ability to overweight specific names. For example, you might hold 70% of your equity allocation in a total market fund and 30% in individual stocks like Thermo Fisher. That way, you capture TMO's upside directly while still maintaining a diversified base.
How does fund size affect Thermo Fisher exposure?
Larger funds hold more total dollars in their Thermo Fisher positions, which can influence the stock's liquidity and institutional ownership profile. A $10 billion ETF with a 2% TMO allocation holds $200 million worth of shares. A $500 million fund with the same 2% weighting holds only $10 million. The larger fund has more influence on the stock's trading volume and can create stronger price support during market downturns because institutional investors are less likely to liquidate such large positions quickly.
From your perspective as an individual investor, fund size affects liquidity and spreads. Larger ETFs tend to have tighter bid-ask spreads, lower trading costs, and better price discovery. Smaller funds might have wider spreads, which can eat into your returns if you trade frequently. But fund size doesn't directly change your personal exposure to Thermo Fisher—that's determined entirely by the weighting and the dollar amount you invest.
Bid-ask spread: The difference between the highest price a buyer is willing to pay for an ETF share and the lowest price a seller is willing to accept. Tighter spreads mean lower trading costs. Larger, more liquid ETFs typically have spreads of just a few cents, while smaller funds can have spreads of 10 cents or more.
What about sector ETFs versus broad market funds?
Sector ETFs concentrate your capital in a specific slice of the economy, which amplifies both gains and losses. A healthcare ETF might allocate 3% to Thermo Fisher and another 50% to similar companies in diagnostics, pharmaceuticals, and biotech. If the sector performs well, your returns will be strong. If regulatory headwinds hit the industry or drug pricing becomes a political issue, the entire fund suffers. You're betting on the sector as much as on any individual holding.
Broad market index funds spread risk across all sectors, which smooths volatility but also limits upside if any single sector outperforms. A total market ETF might hold Thermo Fisher at 0.5% alongside energy companies, banks, tech giants, and consumer staples. If healthcare surges, you capture some of that gain, but the majority of your portfolio is still exposed to whatever the rest of the market does. These funds are designed for investors who want to match overall market returns without making sector-specific bets.
Your choice between the two depends on your risk tolerance and market view. If you believe healthcare will outpace the broader market and you're comfortable with sector-specific risk, a focused ETF makes sense. If you prefer steady, diversified growth without trying to time sectors, a broad market fund is the safer path. You can also combine both approaches by holding a core broad market position and adding smaller sector allocations where you see opportunity.
Try it yourself
Want to run this kind of analysis on your own? Copy any of these prompts and paste them into the Rallies AI Research Assistant:
- Which ETFs have the largest positions in Thermo Fisher, and how much portfolio exposure would I actually get to TMO through each one — is it better to own the stock directly or get diversified exposure through a fund?
- What ETFs give me exposure to Thermo Fisher? Which ones have the highest weighting?
- Compare the top three healthcare ETFs by Thermo Fisher weighting and show me how the rest of their holdings differ—what other stocks am I getting bundled exposure to in each fund?
Frequently asked questions
What ETFs hold the most Thermo Fisher stock?
Healthcare sector ETFs typically hold the largest positions in Thermo Fisher as a percentage of their portfolios, often between 1.5% and 3.5%. Broad market index funds also hold TMO but at lower weightings, usually between 0.3% and 0.8%. The specific funds with the highest allocations change over time as fund managers rebalance and adjust sector exposure.
How do I calculate my actual Thermo Fisher ETF exposure?
Multiply your total investment in the ETF by the fund's TMO weighting percentage. If you invest $10,000 in an ETF with a 2% Thermo Fisher allocation, you have $200 of indirect exposure to TMO. The remaining $9,800 is spread across the other holdings in the fund.
Do TMO index funds offer better exposure than sector ETFs?
Index funds that track broad market benchmarks usually have lower Thermo Fisher weightings than healthcare-focused sector ETFs. If you want concentrated TMO exposure, a sector ETF gives you more. If you want diversified exposure across all industries with some TMO included, a total market index fund is better. Neither is inherently superior—it depends on your goals.
Can I own both Thermo Fisher stock and ETFs that hold TMO?
Yes, and many investors do exactly that. Owning TMO directly gives you full exposure to the stock's performance, while ETFs provide diversified exposure to the broader healthcare sector or total market. Just be aware that you're doubling up on Thermo Fisher, so if the stock underperforms, it affects both your direct holding and your ETF position.
What happens to ETF weightings when Thermo Fisher's stock price changes?
In market-cap-weighted ETFs, a stock's weighting rises when its price increases and falls when its price declines, assuming the fund doesn't rebalance. If Thermo Fisher outperforms the rest of the fund's holdings, its allocation percentage will drift higher over time. Fund managers periodically rebalance to bring weightings back in line with the index they track.
Are there ETFs that focus specifically on life sciences and diagnostics companies like Thermo Fisher?
Some ETFs focus on narrower subsectors within healthcare, such as biotechnology, medical devices, or life sciences tools. These funds may have higher Thermo Fisher weightings than broad healthcare ETFs because they exclude pharmaceutical companies and health insurers. You can research thematic ETFs using a stock screener or fund database to find options that match your specific focus area.
Bottom line
The best ETFs with Thermo Fisher exposure depend on whether you want concentrated sector exposure or broad diversification. Healthcare ETFs give you higher TMO weightings but tie your returns to the sector's performance, while broad market funds offer lower weightings with less volatility. Direct stock ownership delivers full exposure without dilution, but ETFs provide instant diversification and reduce single-stock risk.
If you're building a portfolio and want to understand how different holdings fit together, explore more strategies on the portfolio management page or research specific stocks using the Thermo Fisher stock page.
Disclaimer: This article is for educational and informational purposes only. It does not constitute investment advice, financial advice, trading advice, or any other type of advice. Rallies.ai does not recommend that any security, portfolio of securities, transaction, or investment strategy is suitable for any specific person. All investments involve risk, including the possible loss of principal. Past performance does not guarantee future results. Before making any investment decision, consult with a qualified financial advisor and conduct your own research.
Written by Gav Blaxberg, CEO of WOLF Financial and Co-Founder of Rallies.ai.
