When Atlantic Media launched Quartz as a standalone business site in 2012, it seemed like an odd experiment. The site didn’t even have a traditional home page, and editors said writers would be divided not into traditional beats but instead into “obsessions.” It didn’t even have a mobile app, and still doesn’t (although it is working on one).

Despite all of that, however, Quartz seems to have proven that it’s not some weird skunk works, but a sustainable standalone media entity. In an internal memo that Fortune managed to get hold of, publisher Jay Lauf said the site’s traffic rose by 65% in December to almost 17 million unique visitors, more than The Economist or the Financial Times.

“I think this is proof that we have established a brand that stands for something that gets people coming back,” Lauf told Fortune in a phone interview. “The other thing is the impact of adding more journalists, including a a video team—we launched that in April, and we are already at more than 100 million video views.”

Revenues have also been growing rapidly, climbing by 85% in 2015 after rising by more than 160% in 2014. In the memo, Lauf says that Quartz has already signed deals that will bring in three times as much revenue as it had by the same period last year. “We have secured more revenue by January 19, 2016 than we booked in total for 2014,” the memo also says.

A recent Financial Times piece on Quartz—which said that Atlantic Media has been fielding acquisition offers—estimated that the site had revenues of $15 million. A source within Quartz, however, told Fortune that revenues for last year were closer to $19 million, and that the site is close to being cash-flow positive.

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Lauf wouldn’t comment on the acquisition rumors, except to point to a statement that Atlantic Media provided to the Financial Times, which said: “With Quartz’s tremendous growth trajectory over the last three years, it shouldn’t be surprising that there’s investment interest. We would be remiss in not evaluating opportunities as they arise.”

The price that German media giant Axel Springer paid to acquire Business Insider no doubt sparked some interest at Atlantic Media: the U.S. news startup was bought for $343 million, which valued the company at a massive 9 times revenue. If Quartz were to get a similar multiple, it could be worth as much as $180 million.

A number of large traditional media entities are said to have looked at buying the site, in part because they are trying to find ways to help diversify their revenues away from print publications and declining display advertising.

Quartz also has a large international readership, with about 40% of its traffic and almost 30% of its revenues coming from outside the United States.

Lauf said that despite an overall downward trend in prices for online advertising, Quartz has managed to hold steady, with average CPMs (cost per thousand impressions) as high as $65. “We’re not seeing any downward pressure at all,” he said. “I think that’s because there’s an increasing flight to quality among the kinds of B2B advertisers and high-end brands that make up our base.”

The Quartz publisher said advertising makes up about 90% of the site’s revenue, although it also does a number of premium events, and its Daily Brief email newsletter has about 180,000 subscribers. Like many media companies, Quartz has its own in-house staff who create “sponsored content” or native advertising.

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When it comes to its distribution model, Lauf said Quartz tries to make use of the increasing power of platforms such as Facebook FB and Apple News, but without relying too much on a single platform.

“Our position is we want to elegantly exist wherever our readers are,” Lauf said. “History has shown when try to combat your users habits, it’s a fool’s errand, so need to figure out how to harness that rather than trying to fight it.” One thing in Quartz’s favor, he said, is that “we don’t have a lot of legacy infrastructure to tear down or manage around.” The site is built on an open API or application programming interface, which allows it to direct content to wherever it needs to be.

The site pays attention to Facebook’s power, especially when it comes to pushing video, but “we don’t over-optimize for it,” Lauf said. “It’s not the sole thing we think about or try to build for.” Using multiple platforms makes it easier to be flexible when one changes its algorithm, he says: “Our first full year, LinkedIn was our number one source of traffic, and then they changed their approach and it went to zero. But we never missed a beat.”