From a SCOAP3 Announcement:
Today we have 20.000 reasons to celebrate: since its start in 2014, SCOAP3 has supported the Open Access publication of 20,000 articles. All articles are released under a CC-BY license and are openly accessible on publishers’ websites and the SCOAP3 repository for further distribution. SCOAP3 makes all articles immediately Open Access at no cost or burden for authors thanks to the support of its more than 3,000 members from 43 countries.
SCOAP3 started operation in January 2014 by transitioning several key journals to Open Access. With the recent addition of three journals published by the American Physical Society, it covers almost 90% of all High-Energy Physics journal publications. You can find more details on the SCOAP3 business model, and its financial success in a recently published article.