That's quite different from the way I understand it. You have to specify more exactly what you mean when you say the current price is $1.92. Is it the current

That's quite different from the way I understand it. You have to specify more exactly what you mean when you say the current price is $1.92. Is it the current best (highest) bid, best (lowest) offer, or last traded price (this is generally the displayed price, but there is no guarantee that you can buy or sell at that price, since that depends on current outstanding offers and bids. Suppose the last traded price is $1.92, and the current best bid (highest price anyone is willing to pay) is $1.90 and the best offer (lowest price anyone is willing to sell) is $1.95. You can either decide to buy from the best offer or bid higher than the current best bid and hope to find a seller. Where HFT comes in is in that the increased amount of money and number of participants in the market tends to cause the difference between the best bid and best offer prices ("the spread") to go down, making it cheaper for everyone to enter and exit the market as they wish. This is the market making effect hugh3 referred to above. Please note I am not an expert and may turn out to be wrong on some of this.