Each quarter, the price of that fund will likely vary — sometimes it will be up, sometimes it will be down.
For example, say an investor wants to invest $1,000 every quarter in an exchange-traded fund (ETF) that tracks the S&P 500. Each quarter, the price of that fund will likely vary — sometimes it will be up, sometimes it will be down. The amount of money the individual invests remains the same, so they are buying fewer shares when prices are high, and more shares when prices are low.