Buying and selling at the close and then at the open would have zero net impact on the price.
Gold doesn't need any help going down, the dollar doesn't need any help going up.
The currency market is much much much larger than the gold futures market. Buying and selling a tiny bit of gold would have no impact on the value of dollars.
gold is a 24 hour market.
buying on the close in NY and selling pre-open NY is how they’ve been doing it for a few years. this is how they pull down the value of gold going into the open in NY, thereby propping up the dollar.
the gold market, as of last year, is about 140m ounces/day or about $170b/day.
in comparison, the NY stock exchange is about $28b/day and the equities market is about $191b/day
manipulating the gold market has a very sizable effect on the other markets.
the silver market has a similar, tho lesser effect... now trading about 75:1 to gold (this is very high and should be closer to 40 or 50 to 1)