Why do some closed-end mutual funds trade above or below their net asset values?

Intuition tells us that a mutual fund's net asset value (NAV) (the net value of all assets within the mutual fund's portfolio divided by the number of outstanding shares) should be identical to its market price, but often, the market price of a closed-end mutual fund (a fund with a fixed number of issued shares that can't be altered) will trade either above or below its NAV.

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