Mixing ETFs and Individual Stocks
This article outlines the principles and pitfalls of a hybrid active-passive strategy that combines the diversification of ETFs with the concentrated focus of individual stocks within a single portfolio.
Passive and Active: What to Mix
ETFs are passive assets that track an index or a specific basket of securities. Instead of buying a single stock, you acquire dozens to hundreds of stocks at once, diluting the risk of individual company events across an average. Examples include S&P 500 tracking ETFs in the US market or KOSPI 200 tracking ETFs in the Korean market.
Individual stocks are an active choice where an investor directly selects specific companies and allocates a significant weighting. While aiming for returns better than the market average, the performance or negative news of a single company directly impacts the entire portfolio.
A hybrid strategy places both within a single account. The core idea is to divide roles: diversification is handled by ETFs, while the pursuit of excess returns is assigned to a small number of individual stocks.
The Core-Satellite Structure: A Look at Weighting
The most widely used form is the core-satellite approach. The largest portion of the portfolio (the core) is filled with broad-market ETFs, while a smaller portion (the satellite) is allocated to individual stocks. For example, out of a total capital of $10,000, $8,000 might be invested in a market index ETF, and $2,000 might be divided among 4 individual stocks, with $500 in each.
The advantage of this structure is that the sources of profit and loss are separated. While the core tracks the market average, the performance of the satellite can be evaluated independently. Even if one satellite stock loses half its value, that loss would only amount to $500 of the total, or about 5%.
The weighting itself becomes a risk management tool. By limiting the total allocation to individual stocks to 20-30% of the overall portfolio, even if stock selections are incorrect, the portfolio will not deviate significantly from the market.
The Balance of Risk and Return Created by Mixing
Holding only ETFs makes it difficult to expect returns beyond market performance, while holding only individual stocks increases volatility. A hybrid approach positions itself somewhere in between. The higher the core weighting, the closer the results will be to the market average; the higher the satellite weighting, the more exposed the portfolio becomes to the fortunes of individual stocks.
As a simple example, suppose a core ETF rises 8% in a year and the satellite portion rises 20%. With an 80/20 weighting, the overall return would be 0.8×8 + 0.2×20 = 9.6%. Conversely, if the satellite portion drops 30%, the overall return would be 0.8×8 + 0.2×(-30) = 0.4%, which is underperforming the market but results in a smaller loss than if the entire portfolio were invested in individual stocks.
This calculation demonstrates that the success or failure of a hybrid strategy depends not only on stock selection ability but also on portfolio weighting design.
How to Check for Overlapping Exposure
The most frequently overlooked pitfall in a hybrid portfolio is overlapping exposure. Market-cap-weighted ETFs have a large allocation to large-cap stocks, so if you also buy those same large-cap stocks individually, your actual concentration becomes much higher than intended.
For example, if a certain big tech company accounts for a 7% weighting within an ETF, and you then purchase that same stock as a satellite holding, the total weighting of that single company in your overall portfolio could rise to double digits when combining both sources. You bought the ETF for diversification, but you end up effectively betting on one stock.
Therefore, when selecting satellite stocks, it's advisable to first check the top holdings of your core ETF and, if possible, choose stocks from areas that are either underweighted or not included in the ETF, to preserve the diversification effect.
Real-World Variables: Rebalancing and Costs
Over time, the weightings in a hybrid portfolio can drift. If the satellite portion significantly increases in value, its weighting might swell from 20% to 35%, increasing risk beyond what was intended. This is why regular rebalancing, to restore the original weightings, is necessary.
Costs cannot be ignored either. ETFs incur management fees (expense ratios), and frequently buying and selling individual stocks accumulates transaction costs and taxes. While broad index ETFs might have annual expense ratios in the 0.1% range, some thematic ETFs can be several times higher. Therefore, it's helpful to compare whether you can achieve similar exposure at a lower cost.
Taxation on capital gains and dividends, as well as currency exposure, differ between countries like Korea and the US. If you include international ETFs or US individual stocks, you must also consider that currency fluctuations introduce an additional variable to your returns.
Checkpoints
A hybrid strategy is a method of balancing diversification and concentration through weighting. By tracking the market with a core ETF and attempting to achieve excess returns only with a limited satellite portion, the impact of incorrect stock selections is contained.
In practice, you should check three things: Does the total weighting of individual stocks exceed your set limit? Are your core ETF and individual stocks creating overlapping exposure to the same companies? Do you have a rebalancing rule to restore weightings when they drift?
This article is an educational resource explaining the structure of a strategy and does not recommend the purchase of specific stocks or ETFs. Weightings and costs should be determined by each individual based on their investment horizon and risk tolerance.
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