Free ETF Overlap API — Compare Any Two ETFs

Find out if your ETFs are secretly holding the same stocks. Our free API returns exact overlap percentages, shared holdings with weight breakdowns, and a diversification verdict.

Endpoint

GET https://securitiesdb.com/api/v1/etfs/overlap?etf1=SPY&etf2=IVV

Parameters

Param	Required	Description
etf1	Yes	First ETF ticker (e.g. SPY)
etf2	Yes	Second ETF ticker (e.g. IVV)

Example Response

{
  "status": "success",
  "data": {
    "etf1": "SPY",
    "etf2": "IVV",
    "overlap_pct": 99.7,
    "shared_holdings": 503,
    "etf1_unique_holdings": 0,
    "etf2_unique_holdings": 0,
    "verdict": "Near-duplicate — little diversification benefit",
    "top_shared_holdings": [
      {
        "ticker": "AAPL",
        "name": "Apple Inc",
        "weight_in_etf1": 7.12,
        "weight_in_etf2": 7.14,
        "overlap_contribution": 7.12
      }
    ]
  }
}

Python Example

import requests

url = "https://securitiesdb.com/api/v1/etfs/overlap"
params = {"etf1": "VTI", "etf2": "VOO"}

response = requests.get(url, params=params)
data = response.json()["data"]

print(f"Overlap: {data['overlap_pct']}%")
print(f"Shared holdings: {data['shared_holdings']}")
print(f"Verdict: {data['verdict']}")

# Top shared positions
for h in data["top_shared_holdings"][:5]:
    print(f"  {h['ticker']}: {h['weight_in_etf1']:.1f}% / {h['weight_in_etf2']:.1f}%")

How Overlap Is Calculated

For each stock held by both ETFs, we take the minimum weight in either fund. The overlap is the sum of these minimums, capped at 100%.

overlap = Σ min(weight_in_etf1, weight_in_etf2)

This is the standard methodology used by institutional investors. Two ETFs tracking the same index (e.g. SPY and IVV both track S&P 500) will show ~99% overlap.

Common Use Cases

Portfolio deduplication — Check if your ETFs overlap before adding a new position
Tax-loss harvesting — Find similar-but-not-identical ETFs to avoid wash sale rules
Robo-advisor audit — Verify your robo-advisor isn't double-charging for overlapping funds
Research — Study how different index methodologies lead to different holdings

Try it in the interactive playground →