Published September 4, 2026 · Updated September 22, 2026

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Nasdaq Biotechnology Index Methodology

Direct answer

The Nasdaq Biotechnology Index (NBI) selects constituents from Nasdaq-listed biotechnology and pharmaceutical companies that meet minimum market capitalization and average daily trading volume thresholds. Constituents are weighted by modified float-adjusted market capitalization with concentration limits that prevent any single company from exceeding a specified percentage of the index. The index undergoes a full annual reconstitution and quarterly rebalances.

# Nasdaq Biotechnology Index Methodology

NBI measures Nasdaq-listed companies classified as Biotechnology or Pharmaceuticals under ICB and satisfying Nasdaq's eligibility requirements.

Core current rules

Primary U.S. listing: Nasdaq Global Select Market or Nasdaq Global Market.
ICB: Biotechnology or Pharmaceuticals.
Minimum market capitalization: $200 million.
Minimum ADTV: 100,000 shares over the methodology's measurement period.
General seasoning: three full calendar months.
Annual reconstitution: December.
Quarterly rebalance: March, June, September and December.
Weighting: modified market capitalization.
Maximum individual weight at rebalance: 8%.
Only the five largest securities may exceed 4%.

All qualifying securities are included; the index is not designed around a fixed constituent count.

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