1. Changes in market conditions: the fund manager will adjust his position according to changes in market conditions. If the market is good in a certain quarter, fund managers may increase their positions to get more income. On the other hand, if the market is not good, the fund manager may reduce the position to reduce the risk.
2. Adjustment of investment strategy: Fund managers may increase or decrease positions according to the adjustment of investment strategy. For example, if a fund manager is optimistic about the prospects of an industry or company, he may increase his position in that industry or company. If the fund manager's risk assessment of certain stocks or bonds changes, he may also adjust his position.