Stock Portfolio Tracker

Frequently Asked Questions

What is cost basis and why does it matter?

Cost basis is what you paid (including commissions and reinvested dividends). It determines your taxable gain on sale. The IRS allows specific-lot identification to optimize tax outcomes, essential for long-term taxable accounts.

How concentrated is too concentrated?

A common rule: no single stock above 5-10% of a portfolio. Above 20% in one name introduces meaningful single-stock risk. Employer stock concentration is especially risky because your job and savings depend on the same company.

Should I rebalance after every move?

No. Most research suggests rebalancing annually or when an allocation drifts more than 5 percentage points from target. Frequent rebalancing in taxable accounts triggers unnecessary capital gains and trading costs.

What benchmark should I compare against?

Match the benchmark to your style: S&P 500 for US large-cap, Russell 2000 for small-cap, MSCI EAFE for developed international, AGG for US bonds. Comparing a 60/40 portfolio to the S&P 500 alone is misleading.

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Estimates only. Not investment advice.

Investment Disclaimer: Estimates only. Not investment advice.

This calculator provides estimates for educational purposes only and is not investment advice. Past performance does not guarantee future results. Consult with a qualified financial advisor before making investment decisions. All investments carry risk, including potential loss of principal.

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How This Calculator Works

Enter up to ten positions, each with a ticker, share count, cost basis (price paid per share), and current price. The tracker values every holding at current price, subtracts cost to get each position's gain or loss in dollars and percent, and rolls them up into a portfolio total: total value, total cost basis, total gain/loss, and overall return. It computes each position's allocation - its share of total value - so you can spot concentration, and it ranks holdings to surface your top three winners and top three losers by percentage return. Rows left blank or without a positive share count and price are simply ignored.

Formulas Used

Position cost = shares × cost basis; position value = shares × current price; gain = value − cost; gain% = gain ÷ cost × 100. Portfolio total value and total cost are the sums across positions, total gain = total value − total cost, and total return% = total gain ÷ total cost × 100. Allocation% for each holding = position value ÷ total value × 100. Winners and losers are found by sorting all positions on gain% and taking the best and worst three.

Worked Example

Hold 50 AAPL bought at $150, now $210: cost $7,500, value $10,500, a +$3,000 gain (+40%). Add 20 NVDA bought at $450, now $900: cost $9,000, value $18,000, a +$9,000 gain (+100%). Across just these two, total cost is $16,500 and total value $28,500, a +$12,000 gain (+72.7%). NVDA is now about 63% of the two-stock book and the clear top winner - a textbook case of a runaway position quietly dominating the portfolio's risk.

Common Mistakes

Entering total dollars spent instead of per-share cost basis in the cost field, which scrambles the gain math.

Letting one winner balloon unchecked - a 20% target can drift to 35%+ after a strong year, concentrating risk.

Forgetting commissions in the cost basis; they raise your true cost and reduce reported gains.

Reading percentage gains without dollar context - a small position up 200% matters less than a large one up 20%.

Tips & FAQ

Cost basis is the price paid per share including commissions; with multiple lots, use the weighted-average cost. On taxes, short-term gains (held one year or less) are taxed as ordinary income at 10–37%, while long-term gains get the 0/15/20% rates - holding past the one-year mark can save 10–20 points. Losing positions can be harvested to offset gains (up to $3,000 a year against ordinary income), but watch the 30-day wash-sale rule. Common position-sizing guides: single stock 5–10% max, any sector 25–30% max, a 5–10% cash buffer. Educational only, not investment advice.

Frequently Asked Questions

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