Finance has a bad rap. And whether you think that reputation is well-deserved or utter baloney, one thing is certain: The world of finance is changing. What has long been viewed as an insiders’ club is now increasingly available to ordinary people. This change has come not because someone in charge had a change of heart, but rather because technology has rendered much of the old gatekeeping obsolete.

Financial markets are currently demonstrating record volatility. Many people are losing money in these rocky times — while others are profiting more than ever. Today’s tools are helping some ordinary people to leave the former group and become part of the latter.

“No one has a consistently reliable crystal ball,” says financial advisor Spencer Sherman, who founded financial consulting firm Abacus Wealth, which today manages more than $3 billion in assets on behalf of its clients. Sherman is a proponent of evidence-based investment strategies, such as carrying a diversified portfolio and regularly “rebalancing” (more on that in a moment).

Today’s tools allow anyone with a few dollars and an internet connection to follow Sherman’s suggestions, which in the past might have been inaccessible to those not working with a registered trader or formal advisor. This new era brings risk as well as opportunity.

An array of powerful tools has recently become available to middle- and low-income people who want to participate in financial markets. But the sheer number of options can be a deterrent to novices. At the same time, these new tools have opened doors for small-dollar traders in ways that remain poorly understood.

It is now possible to purchase a “fractional” share of stock, which just means part of a share. Platforms such as Fidelity and Robinhood allow users to buy, for instance, $100 worth of Tesla, even though a share of Tesla is currently trading for around three times that much. It used to be that, unless you could buy at least a whole share, you couldn’t have any at all. In this way, fractional investing is revolutionary. (Robinhood grew famous both for fractional investing and for a widely publicized controversy: The platform was charged by the SEC for misleading customers with the claim that they did not charge commission. Robinhood was not the first, and is not the only, platform to offer fractional shares.)

Fractional investing is particularly powerful when combined with another tool that has only recently become available to small-dollar investors.

“Rebalancing is the maintenance we perform on our portfolios to keep them in our desired balance,” says Spencer Sherman. Rebalancing, which can now be done with a swipe in an app, is a process that financial advisors have long performed regularly on the portfolios of wealthy individuals.

But what exactly is rebalancing?

Let’s say you have $100 that you’ve decided to invest in stocks. After some research, you determine that you want 25% in Apple, 25% in Disney, 25% in Ford and 25% in Tesla. Thanks to fractional investing, you can actually buy $25 worth of each, regardless of share prices. So you log into your investment platform of choice and make your purchases.

But almost as soon as you’ve bought your fractional shares, those percentages start to change because the value of the shares you’ve acquired fluctuates continuously whenever markets are open. Some shares are now worth more than 25% of your portfolio; others are worth less. Eventually, if you want to maintain your desired four-way split between those companies, you’ll need to rebalance, which means selling some shares and buying others in order to return to your desired allocation.

But who cares? Why is this important?

It’s important because it allows investors to follow a basic blueprint for success. There is very little in the world of finance that is uncontroversial — as even the savviest financial minds can disagree about strategy — but one concept is very rarely disputed: Buy low, and sell high.

“The beautiful thing about rebalancing is that it forces us to trim securities from the categories that have gone up in value, and then to use those proceeds to buy more securities in the categories that have gone down,” says Sherman. “In other words, it is a system for buying low and selling high.”

Rebalancing used to be an extremely complicated and time-consuming process that was performed manually by human traders. Now, the single swipe of an app can rebalance a portfolio instantly. Small-dollar investors have access to an automated technology that helps them buy low, and sell high.