Share your insights or perspective on the financial matter presented in the input.

What exactly do fund managers of index trackers do?
From How are indexes weighted?: Market-capitalization weighted indexes (or market cap- or cap-weighted   indexes) weight their securities by market value as measured by   capitalization: that is, current security price * outstanding shares.   The vast majority of equity indexes today are cap-weighted, including   the S&P 500 and the FTSE 100. In a cap-weighted index, changes in the   market value of larger securities move the index’s overall trajectory   more than those of smaller ones. If the fund you are referencing is an ETF then there may be some work to do to figure out what underlying securities to use when handling Creation and Redemption units as an ETF will generally have shares created in 50,000 shares at a time through Authorized Participants. If the fund you are referencing is an open-end fund then there is still cash flows to manage in the fund as the fund has create and redeem shares in on a daily basis. Note in both cases that there can be updates to an index such as quarterly rebalancing of outstanding share counts, changes in members because of mergers, acquisitions or spin-offs and possibly a few other factors. How to Beat the Benchmark has a piece that may also be useful here for those indices with many members from 1998: As you can see, its TE is also persistently positive, but if anything   seems to be declining over time. In fact, the average net TE for the   whole period is +0.155% per month, or an astounding +1.88% pa net   after expenses. The fund expense ratio is 0.61% annually, for a   whopping before expense TE of +2.5% annually. This is once again   highly statistically significant, with p values of 0.015 after   expenses and 0.0022 before expenses. (The SD of the TE is higher for   DFSCX than for NAESX, lowering its degree of statistical   significance.) It is remarkable enough for any fund to beat its   benchmark by 2.5% annually over 17 years, but it is downright eerie to   see this done by an index fund. To complete the picture, since 1992 the Vanguard Extended Index Fund   has beaten its benchmark (the Wilshire 4500) by 0.56% per year after   expenses (0.81% net of expenses), and even the Vanguard Index Trust   500 has beaten its benchmark by a razor thin 0.08% annually before   (but not after) expenses in the same period. So what is going on here? A hint is found in DFA's 1996 Reference   Guide: The 9-10 Portfolio captures the return behavior of U.S. small company stocks as identified by Rolf Banz and other academic   researchers. Dimensional employs a "patient buyer" discount block   trading strategy which has resulted in negative total trading costs,   despite the poor liquidity of small company stocks. Beginning in 1982,   Ibbotson Associates of Chicago has used the 9-10 Portfolio results to   calculate the performance of small company stocks for their Stocks,   Bonds, Bills, and Inflation yearbook. A small cap index fund cannot possibly own all of the thousands of   stocks in its benchmark; instead it owns a "representative sample."   Further, these stocks are usually thinly traded, with wide bid/ask   spreads. In essence what the folks at DFA learned was that they could   tell the market makers in these stocks, "Look old chaps, we don't have   to own your stock, and unless you let us inside your spread, we'll   pitch our tents elsewhere. Further, we're prepared to wait until a   motivated seller wishes to unload a large block." In a sense, this   gives the fund the luxury of picking and choosing stocks at prices   more favorable than generally available. Hence, higher long term   returns. It appears that Vanguard did not tumble onto this until a   decade later, but tumble they did. To complete the picture, this strategy works best in the thinnest   markets, so the excess returns are greatest in the smallest stocks,   which is why the positive TE is greatest for the DFA 9-10 Fund, less   in the Vanguard Small Cap Fund, less still in the Vanguard Index   Extended Fund, and minuscule with the S&P500. There are some who say the biggest joke in the world of finance is the   idea of value added active management. If so, then the punch line   seems to be this: If you really want to beat the indexes, then you   gotta buy an index fund.