On these kinds of days the person that cares enough can look for an anomaly or two in the market and scalp a couple of percentage points once the market kicks back into gear in a day or two. In the case of today the idea would be to buy or sell a position and reverse Monday. Frankly I don't care enough to do it myself, but in times past it was one of the ways used to make a bit of coin when living in Argentina. On days when the local market was open and the USA closed, the floor brokers would try and pump a local dog-stock that would normally be held back by foreign money transactions. Not quite the same scenario today, but there are enough parallels to remind me of the heady days in Buenos Aires. Memories, eh?
So check out how GRZ is up 18% on low volume. The idea would be to sell a few shares here, then repurchase at $0.50 on Monday or Tuesday.
The example on the opposite side of the trade is DMM.to. On the quietest volume day of the month it's decided to buck its recent strong uptrend. If you think this is coincidence I recommend you never trade the stock market ever again. Down 21c at $3.39 right now, the idea would be to buy a few shares and then sell them for the quick'n'happy flip when the market returned to normal, presumably at $3.60.
Just two examples of the trade available and they get chosen because they're two stocks front'n'centre on my radar at the moment. Pick your own example, as it's likely to be just as good.