Sorry, there is an upstream delay in HKEX End of Day data. They are still working on it now.
This is simply the average portfolio cost of all trading days in the year so far.
Example: There are three trading days so far in year 2017 [2017-01-03, 2017-01-04, 2017-01-05] and the portfolio costs are (SGD15), (SGD15) and (SGD30) respectively.
Then the average cost would be (15 + 15 + 30) / 3 = SGD20.
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