Mutual fund managers have cash for several reasons:
1)A huge influx of cash that they need time to figure out how to invest.
2)Keeping some available for opportunities that could come along soon.
3)If redemptions start running higher than normal, they would rather pay cash than sell their positions to meet them
4)To protect the fund's shareowners in volatile markets.
I remember AGTHX was 30% in cash in 2000 and 2001. I don't think their shareholders got too pissed when they were buying short-term Treasuries instead of ORCL................