A broader market sell-off during the last quarter of 2018 has made the new year a great time to be buying stocks. Sure, there's no guarantee that stocks won't continue falling over the next three to six months, but it's very likely that opportunistic investors who are buying amid this sell-off will be happy they did so five to 10 years from now. After all, stocks have risen nicely over the decades, despite the Great Recession, bubbles, terrorist attacks, and wars.

With that said, if you're brave enough to get a bit greedy while the rest of the market is fearful, here's one stock to consider: financial-technology company Square (NYSE:SQ). On the heels of accelerating growth and strong product launches, Square stock looks like a good buy, particularly after its recent sell-off.

Here are three reasons to consider adding Square stock to your portfolio.

An employee and customer interact with the two displays included with Square Register

Square Register. Image source: Square.

1. Its momentum is undeniable

In Square's third quarter of 2018, the company reported some impressive growth. Revenue rose 51% year over year, and adjusted revenue increased 68% over the same timeframe. These growth rates compare with 48% and 60% year-over-year growth in the second quarter of 2018, respectively. 

Driving home how significant Square's momentum is, this was the company's sixth quarter in a row of accelerating revenue growth.

2. Square's newest products are compelling

In recent years, Square has launched some significant new products, showing how the company still has room to expand its ecosystem and scale its business.

In October 2017, Square launched Register -- a high-end checkout product. Then last spring, Square launched Square for Restaurants, a fully integrated point-of-sale system for restaurants. These products extend a growing list of impressive execution with product launches in recent years. Other major products launched since 2014 include Square Capital, Virtual Terminal, Caviar, Invoices, Instant Deposit, and Build With Square APIs (application programming interfaces).

3. Larger sellers are coming to Square

Finally, one way Square could keep up an uncanny growth rate in 2019 is with the company's momentum with larger sellers. Though Square initially gained popularity by catering to small businesses with easy-to-use payment processing tools, the company has since expanded to more comprehensive offerings that are attracting larger sellers.

To that end, 24% of Square's gross payment volume in its third quarter came from sellers with $500,000 in annualized gross payment volume (GPV) or more. That figure was up from 16% in the third quarter of 2016 and 20% in the third quarter of 2017. Furthermore, Square said in its third-quarter shareholder letter that GPV from sellers with $125,000 or more in annual sales was up 41% year over year, while overall gross payment volume increased 29% year over year.

Given Square's strong overall growth, its impressive cadence of new product launches, and its momentum with larger sellers, the stock's 42% decline gives investors interested in the stock a great entry point into a company with strong tailwinds.

Check out the latest Square earnings call transcript.