During the rewrite, the share of Facebook's traffic that was monetizable shrank as web declined and mobile grew.

The claim is that during Facebook's rewrite of its mobile app (around 2012), the share of Facebook's traffic that was monetizable shrank, because desktop web, where ads were shown, declined while mobile, which carried little or no advertising, grew. True: Facebook's 2012 S-1 or filings and contemporaneous reporting show mobile usage growing fast while mobile was barely monetized, so that the monetizable share of usage fell. Mostly true: the trend is right, but a detail is slightly off, such as absolute web usage holding steady rather than 'shrinking', or the timing being slightly off. Mixed: mobile grew, but evidence on whether the monetizable share actually fell is split. Mostly false: mobile was already substantially monetized, or the web share did not meaningfully fall, so the claim distorts the situation. False: records show the monetizable share of traffic did not fall during that period.

Set before the research began.

1. E1 Form 10-Q U.S. Securities and Exchange Commission (Facebook, Inc. filing) Own record

   “the overall number of ads delivered decreased 2% year-over-year despite a 10% increase in DAUs and despite an increase in ads per page resulting from product changes, as DAUs on personal computers in the United States declined.”

2. E2 Free Writing Prospectus - SEC.gov U.S. Securities and Exchange Commission (Facebook, Inc. filing) · 9 May 2012 Own record

   “We believe this increased usage of Facebook on mobile devices has contributed to the recent trend of our daily active users (DAUs) increasing more rapidly than the increase in the number of ads delivered.”

3. E3 FB-9.30.2012-10Q U.S. Securities and Exchange Commission (Facebook, Inc. filing) · 30 September 2012 Own record

   “During the third quarter of 2012, the number of DAUs using personal computers increased modestly compared to the second quarter of 2012, but in certain key markets such as the United States and Europe the number of DAUs using personal computers was essentially flat quarter-over-quarter after having decreased modestly during the second quarter of 2012.”

4. E4 Facebook Reports Fourth Quarter and Full Year 2012 Results Facebook, Inc. (via Meta Investor Relations) · 30 January 2013 Own record

   “Mobile revenue represented approximately 23% of advertising revenue for the fourth quarter of 2012, up from approximately 14% of advertising revenue in the third quarter of 2012”

In its May 2012 prospectus, Facebook said rising mobile usage had contributed to daily active users growing faster than the number of ads delivered (E2). That means a smaller share of usage was being monetized. A Facebook 10-Q reports that ads delivered fell 2% year-over-year even though daily active users rose 10%, as daily active users on personal computers in the U.S. declined (E1). However, the Q3 2012 10-Q says personal-computer daily active users rose modestly overall and were flat in the U.S. and Europe after a modest Q2 decline (E3). Mobile also rose from about 14% to 23% of ad revenue by Q4 2012 (E4), so the trend is right but 'web is shrinking' overstates it, and the evidence comes only from Facebook's own filings.