Board, closed-end mutual funds, limited partnerships, royalty trusts, non-U.S. incorporated stocks (other than the benefits driven incorporations described above), foreign stocks, and American Depositary Receipts (ADRs). Annual reconstitution Russell rebalances its indexes once each year in June, called "reconstitution". The reconstitution consists of updating the global list of investable stocks and assigning them to the appropriate indices. The Russell indexes do not immediately replace a company that merges with another firm or has its stock delisted. However, Russell adds initial public offerings (IPOs) on a quarterly basis, capturing these stocks in a systematic way. Abnormal trading volumes caused by index fund managers re-balancing their portfolios has a history of significant market impact during the last few seconds before the New York Stock Exchange and NASDAQ closing prices are determined. The index rebalance is typically scheduled for the closing price on the last Friday in June. Primary indexes In addition to the primary indices listed below, Russell publishes Value and Growth versions of each U.S. index. This divides each index roughly in half, separating companies classified as value stocks from those classified as growth stocks. Companies can appear in both the value and growth versions of an index, though the total number of shares between the value and growth versions will equal the number in the main index. The primary indices are: Russell 3000 Index: The Russell 3000 Index measures the performance of the largest 3,000 U.S. companies representing approximately 98% of the investable U.S. equity market. Russell 2500 Index: A mid-cap to small-cap index of the bottom 2,500 stocks in the Russell 3000 Index. Russell 2000 Index: The small-cap benchmark index of the bottom 2,000 stocks in the Russell 3000 Index. Russell 1000 Index: The large-cap index of the top 1,000 stocks in the Russell 3000 Index. Russell Top 200 Index: The mega-cap index of the very largest 200 stocks in the Russell 3000 Index. Russell Top 50 Index: Measures the performance of the 50 largest companies in the Russell 3000 Index. Russell Midcap Index: The bottom 800 stocks in the Russell 1000 Index. The Russell Top 200 Index plus the Russell Midcap Index yields the Russell 1000 Index. Russell Microcap Index: A micro-cap index of the stocks ranked from 2,001-4,000 in the Russell indexing universe, consisting of capitalizations ranging from about $50 million to $2.5 billion. Hence, this is an index of the 1,000 smallest Russell 3000 stocks, plus