In general this fund follows the market.Like the dow was up 259 points Friday Dec 5, so the fund price is based at the close of each business day. Which in this case the fund price rose .41 cents per share.

So, if you want to sell shares you sell when the dow is up before the market closes. Then the price will be based on the market at the business day close. On the same token, if you want to buy shares you buy when the market has a big down day.