If the index goes up by 10%, will my fund grow by 10%?
Not necessarily. Indices are often quoted without dividends whereas the tracker fund performance normally includes dividends. Tracker funds have management charges which are not incorporated in the index performance. Finally, the index performance is normally worked out as the performance at the close of market on a particular day, whereas most tracker funds are valued at midday. Over the long term, the fund performance should be very similar to that of the index, but in the short run they can deviate.