Answer:
The Journal entry is as follows:
Fair value adjustment A/c    Dr. $20,000
To unrealized holding gain or loss-income   $20,000
(To record the adjustment)
Workings:
Ending balance = equity portfolio value - cost
             = $160,000 - $132,000
             = $28,000
Necessary Adjustment = Ending balance - Beginning balance
                   = $28,000 - $8,000
                   = $20,000
