IPO offers access to the newest publicly traded stocks in an ETF wrapper. It adds a new company to its basket within 90 days of listing and removes a firm after three years of public trading. The largest new entrants can be included a week after their IPO date. The resulting portfolio complements the overall equity market, as its weighted average market cap will ordinarily be far smaller, and its constituents may not be included in major indexes for a few months. The small number of eligible securities can make for a concentrated portfolio. Index constituents have a 10% issuer cap and are reviewed quarterly. Post-IPO liquidity can be a challenge for market makers looking to create new shares, so keep a sharp eye on trading spreads.