Scalping: Small Quick Profits Can Add Up. The main premises of scalping are lessened exposure to limit risk: A brief exposure to the market diminishes the probability of running into an adverse event. Smaller moves are easier to obtain: A bigger imbalance of supply and demand is needed to warrant bigger price changes. For example, it is easier for a stock to make a 10 cent move than it is to make a $1 move. Smaller moves are more frequent than larger ones: Even during relatively quiet markets, there are many small movements a scalper can exploit. When scalpers trade, they want to profit off the changes in a security's bid-ask spread. That's the difference between the price a broker will buy a security from a scalper (the bid) and the price the broker will sell it (the ask) to the scalper. So, the scalper is looking for a narrower spread. But in normal circumstances, trading is fairly consistent and can allow for steady profits. That's because the spread between the bid and ask is also steady, as supply and demand for securities is balanced.