I recently published a post in which I estimated the effective database sizes for Family Tree DNA, 23andMe, and MyHeritage using the published database size at AncestryDNA, which was 3 million at the time. On 22 April, 2017, AncestryDNA announced via their Twitter and Facebook feeds that their database had reached 4 million people tested. That means I underestimated the sizes of the other databases. The updated values are below. (Note: I earn a small commission if you purchase through the links in this post. The cost is the same for you. Click here for more information.)
Please see the original post for details of the analysis.