Here is a comprehensive summary of the article about the Invesco QQQ ETF:

Invesco QQQ (ticker: QQQ) is one of the world's most popular exchange-traded funds, designed to replicate the performance of the Nasdaq-100 index by holding the same stocks in the same proportions. Launched on March 10, 1999, it is the most traded fund tracking this index, managing approximately $500 billion in assets as of July 2026. The fund's ticker symbol has an interesting history, having briefly changed to "QQQQ" in 2004 before reverting back to "QQQ" in March 2011. In December 2025, the fund underwent a major structural transformation, switching from a unit investment trust to a more flexible open-ended ETF, which now allows it to reinvest income, participate in securities lending, and use custom redemption baskets. This change also shifted governance to a board of trustees and reduced the expense ratio from 0.20% to 0.18%. These updates make the fund more operationally efficient and cost-effective for everyday investors.