What is portfolio rebalancing
Fund managers are
principally interested in the securities that they are currently holding,
and in securities which are constituents of indices not currently held,
but against which the fund manager is measured.
This holdings data can be presented in a number of ways (e.g. nominal shares held or value of holdings in base or local currency), but the most useful for portfolio modeling are the percentages of the fund that each holding represents. In addition, the data Is generally grouped using security classifications such as market or industry in order that a fund manager can look at his composite holdings in industrial sectors. Thus the fund manager can see both where he is and not is invested in particular stocks, and also where he is over- or underweight with respect to the index for industries and/or stocks.
The amount of effort required in order to provide this type of analysis should not be underestimated. In addition to the initial system set up, the ongoing maintenance of the data, in terms of ensuring that fund positions are correct, and that benchmark data is up to date, is considerable. These systems are very specific to the asset management industry, and are characterized by their voracious appetite for accurate data. Indeed, even within the asset management company itself, the systems and data required are very specific to each department.
Fund managers and analysts are basically interested in any and all information that will affect the values of their portfolios. Although they are mainly focused on the long term investment horizon, many active managers use real-time news and data services to monitor changes in market conditions, with a view to switching between securities to take advantage of perceived opportunities.
Traditionally, the fund managers main guide to his position has been his valuation report, which might display his current holdings in nominal, value and percentage terms. As technology advances, and data suppliers become increasingly able to provide key data such as index constituents and their weightings, fund manager tools are becoming increasingly sophisticated.