Even though Facebook (META -4.13%) reported a decrease in the time users spent on its platform during the fourth quarter, investors seemed pleased by the social network's performance -- at least judging by the stock's gain of as much as 4.3% on Thursday morning. Investors were likely happy with Facebook's soaring revenue and its optimistic outlook for 2018.

Facebook's earnings call, which took place shortly after its earnings release went live, provided a closer look at the factors behind the quarter's strong numbers. But it also shed some light on the company's rationale behind recent changes, and likely helped investors brush aside Facebook's negative user trends.

Here are four of the most insightful takeaways from the call.

Four young people using their smartphones

Image source: Getty Images.

Getting serious about News Feed quality

Facebook stock took a hit in January after the company announced major changes to its News Feed that would deprioritize public content, including videos and posts from publishers and businesses. The changes, which were meant to encourage more social interaction at the expense of passive consumption, would have a negative impact on time spent on the social network, Facebook CEO Mark Zuckerberg predicted.

He was right. During the earnings call, Zuckerberg revisited the subject, highlighting how intent Facebook is on improving the News Feed experience for users:

We estimate these updates decreased time spent on Facebook by roughly 5% in the fourth quarter. To put that another way: we made changes that reduced time spent on Facebook by an estimated 50 million hours every day to make sure that people's time is well spent. That's how serious we are about this.

Looking beyond "time spent" on Facebook

Though management expects News Feed changes to reduce the time users spend on Facebook, this isn't a metric investors should give much weight.

Zuckerberg explained:

So I want to be clear: the most important driver of our business has never been time spent by itself. It's the quality of the conversations and connections. And that's why I believe this focus on meaningful social interactions is the right one.

This was obviously good news for investors.

Sandberg puts it as bluntly as possible

If it wasn't already clear enough that management doesn't want investors to worry about News Feed changes, Facebook COO Sheryl Sandberg drove the point home, explicitly stating that News Feed changes will not negatively impact revenue:

We're not doing this to be positive or negative for revenue, we're doing it because it's the right thing for our community. But the impact it has on monetization is certainly not clearly negative.

Instagram: "A very big opportunity"

Facebook may be the company's bread and butter, but Instagram is quickly growing into an important part of Facebook's overall business. Hitting 800 million monthly active users and 500 million daily active users in September, the photo- and video-sharing app is undeniably in the midst of strong growth.

This has investors and analysts wondering to what extent the app will bolster Facebook's business. Fortunately for Facebook shareholders, management is adamantly bullish about the opportunity on the platform.

A group of young people taking a selfie while eating pizza

Image source: Getty Images.

"On the business side, I think we have -- are both please[d] [with] the results but [also] see a very big opportunity in front of us," Sandberg said. "We have 6 million advertisers on Facebook, which means that we have a lot of opportunity on Instagram, where we only have 2 million advertisers, to grow their engagement with us and their spend."

The opportunity for Instagram's Stories format is particularly compelling, with over 300 million daily active users for the highly immersive format, Sandberg said. She added that Stories is "pretty exciting from a sales point of view because it has a lot of potential. It's full screen, it's authentic, it's very engaging."

Though the conference call certainly helped provide some interesting insight into Facebook's business, it primarily played the important role of easing concerns surrounding the company's recent News Feed changes.