A popular stock-market adage is 'Time in the market is more important than timing the market'. It may be a popular principle but unfortunately not many observe it in practice. Due to some quirk in human nature, we tend to be overconfident of our ability to predict the future. So we end up timing the market. Or at least trying to.
The curious thing about market timing is that the market almost unfailingly moves in the opposite direction to what you would expect. If you buy shares in a company thinking that 'this' is the right time, you are appalled by the fact that the stock starts to fall just after you buy it. Similarly if you sell out your shares in a company because you have a strong gut feeling that it's going to collapse, you find it racing ahead of just about everything.
If you think you are immune to this behavior just because you invest in mutual funds rather than directly in stocks, you are mistaken. Mutual funds investors frequently try to time their systematic investments in response to the market's ups and downs. When the market is falling, they stop their SIPs. When it is rising, they increase their SIP amounts. This invariably backfires.
SIPs work best when the markets are volatile. When the markets are high, you buy less units of your mutual funds through SIPs. When the markets are down, you buy more units for the same amount. This enables you to average your investment cost over time. But if you stop SIPs when the markets are down, you miss out on lowering your total investment cost. And if you increase your SIP amounts when the markets are on the rise, you keep averaging your overall cost upwards.
Now you may say that the solution to this problem is to do just the opposite: stop with SIPs when the markets are rising and increase the SIP amounts when they are falling. Unfortunately, timing the market in this manner is just as unfruitful. First, it is counter-intuitive. Many investors will have difficulty in carrying through their decision to invest when the markets are down and sell when they are up. And second, you can never really know how long the market may keep going up or falling. All in all, it's quite unproductive to time the market.
The beauty of SIPs is that by definition they prevent you from timing the market. SIPs are about discipline. You decide an amount and a frequency, which in most cases is monthly. Then you keep investing in the mutual fund of your choice, irrespective of where the market is. Of course, you can increase your SIP amount yearly as your pay increases but then invest it evenly till the next revision. Since the markets are volatile, you will naturally benefit from the power of rupee cost averaging, which will bolster your returns.