Reddit CEO Yishan Wong. Yishan Wong / Quora Since Facebook changed its News Feed algorithm to focus more on news and less on cute cats and other memes, it appears to have stolen a huge share of referred traffic on the internet — from Reddit.

Traffic referrals are the lifeblood of the web. Publishers need incoming traffic from big, popular sites to survive, and for years Reddit has been one of the biggest sources of outgoing links to juicy content.

But suddenly, Reddit has dropped off, at least in terms of its overall share of internet traffic.

Here's a chart from Parse.ly, the web traffic analytics company (below). It shows that Google dominates the distribution of traffic on the web, and that Facebook is now a healthy second:

Parse.ly

Note that Reddit is still huge, but that "huge" is relative on the web — it's distinctly second-rung to "gargantuan."

Yesterday we noted that Reddit's traffic is actually going up — it saw an 83% increase, to 731 million unique visitors in 2013 — but its share of traffic declined in the same period, according to data from Shareaholic, which measures social media sharing traffic. The decline was a drop of 36% year-over-year, Shareaholic says:

Shareaholic

What the heck is going on? Facebook, that's what.

This chart from Parse.ly shows how Facebook has recently become a referrer of more than 5% of all web clicks:

Parse.ly

Parse.ly's data covers over 5 billion pageviews on hundreds of media properties. The company says:

The results are pretty clear. Sites that use Parse.ly analytics are showing significant changes in traffic from Facebook. Over 40% of Parse.ly-enabled sites have experienced a 30%-or-more growth in traffic from Facebook in 2013. Over 60% of our sites have seen a 10%-or-more bump from the social network.

Over the last year, Reddit went from providing 0.33% of the web's traffic in December 2012 to 0.21% in December 2013 — a 36% drop, according to Shareaholic.

What is jarring here is that Reddit — a site dedicated to sharing stuff — only got bigger in terms of total traffic in 2013, but appears to have become less important in terms of shared traffic over the same period.

Reddit may also be hoarding more of its own traffic.

A few things changed on Reddit in 2013. More of Reddit's top posts are discussions that feature few links, such as its "ask me anything" series in which famous people like Bill Gates or President Obama take questions from the public. And one of Reddit's more infamous 2013 posts was this thread on the Boston Marathon bombing, which contained a bunch of incorrect information.

Plus, news organizations — Business Insider included — now more frequently use Reddit as a source of news rather than a source of traffic. So other publishers are linking in to stuff that is already on Reddit; previously, Reddit users linked out to things they found elsewhere.

Disclosure: The author owns Facebook stock.