Tax-Loss Harvesting in a Bull Market

A rising market does not mean every security—or every purchase lot—is above basis. Index leadership can be narrow, sectors can diverge, and a recent contribution can be underwater even while the overall position shows a large gain.

That makes bull-market harvesting possible. It does not make every red lot worth selling.

Look Below the Position-Level Return

Suppose an investor has owned an ETF for years and adds shares monthly. The original lots may have large gains, while a purchase made near a recent high is down 8%. The brokerage's position view blends those lots together and may show a positive return.

A lot-level view separates:

• adjusted basis and current value;
• acquisition date and holding period;
• unrealized gain or loss;
• recurring purchases that can create a wash sale;
• the specific shares available for sale.

This is the same pattern covered in unrealized losses hidden inside winning positions.

A Conditional Example

An investor owns a healthcare ETF position that is up overall, but one recent lot has a $4,000 unrealized loss. The investor also expects to realize a $4,000 long-term gain while rebalancing.

If the loss lot is sold, the loss is not washed out, and it offsets a gain otherwise taxed at 15%, the potential current federal tax reduction is $600. That is a deferral estimate, not guaranteed lifetime savings. The replacement's lower basis can create more future gain, and fees, state tax, tracking difference, or an unusable carryforward can change the outcome.

The trade also needs an acceptable replacement. Two funds can have similar labels and still differ in index methodology, holdings, concentration, fees, liquidity, and risk. The IRS does not publish a universal safe list for “substantially identical” funds.

Why Bull Markets Create Loss Lots

Common sources include:

• recent purchases made near a local peak;
• dividend-reinvestment lots acquired at different prices;
• a lagging sector inside a rising broad market;
• small-cap, international, or factor exposure moving differently from large U.S. stocks;
• company-specific declines inside a diversified portfolio.

These are candidates for review, not a reason to manufacture turnover. A small loss may not justify spreads, fees, tracking error, or additional recordkeeping.

Coordinate the Sale With Real Portfolio Needs

Bull-market harvesting is most defensible when it supports a decision the portfolio already needs: rebalancing, reducing concentration, changing an investment thesis, or offsetting a planned taxable gain.

Before selling, ask:

1. Which exact lot will be identified?
2. What current gain or future use gives the loss value?
3. Is the loss large enough after costs?
4. What replacement preserves suitable exposure?
5. Are there purchases in any relevant account during the 61-day window?
6. How does the lower replacement basis affect future tax?

For the yes-or-no framework, use when not to harvest. For monitoring cadence, see continuous versus annual tax-loss harvesting.

Bottom Line

Bull markets can contain usable tax losses because portfolios are built from individual lots, not a single index return. The opportunity becomes valuable only when the loss is material, the replacement is suitable, the wash-sale review is complete, and the tax benefit exceeds the trade's costs and future consequences.