Cuban is taking issue with the fact that in September Facebook changed its newsfeed algorithm to deliver more relevant posts in users' newsfeed and to cut down on spam. The concern is that brands now will have to pay to make sure their messages are seen by users. (Read More: Facebook Drops as Employees Sell Shares.)

Now Facebook and Cuban are debating the value of the news feed changes.

Here's the latest exchange:

Facebook's statement:

"There's a lot of misinformation going round about changes to news feed. To be clear — we did not change news feed so we could charge to promote posts. This meme is totally false. News feed is built to show relevant content. A few times a year we perform quality checks on the news feed algorithm to ensure high-quality and relevant posts. Based on a recent quality check, we made an adjustment to the news feed algorithm to respond to the negative feedback signals of spam and people hiding posts. Current signals show the adjustment has been successful — median reach of Pages has remained the same, while spam complaints and stories hidden by users have fallen significantly."

Cuban responded to Facebook's statement, sending me this in an email:

"FB's comment is consistent with what I said in the interview. I never said they changed anything to increase revenue. I said that the way FB is set up currently for the distribution and consumption of posts is far from efficient and not in the best interests of brands. The solution is simple. All they have to do is add a sort/filter option by liked page and everyone would have the chance to see every post quickly and easily and brands wouldn't feel the pressure to have to pay to enhance their opportunities to reach the people who have proactively liked their brands. In addition, it would get rid of all the real estate currently assigned to sponsored posts."

In response to Cuban, Facebook said, "We implemented the exact change he requested this week."

-By CNBC's Julia Boorstin

@JBoorstin

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