Seasonality
The revenue spike that isn't about you
A site we run posted a 6x RPM day with no extra traffic behind it. Before you go looking for what you did right, check the calendar and check a second site.
By Mario Bailey · Published
On the last business day of a quarter, a site we run earned six times its normal RPM. It is tempting to read a day like that as a breakthrough and try to reproduce it. It was not a breakthrough. It was advertisers emptying quarterly budgets, and here is how we knew.
The day, taken apart
On June 29, a business site we run posted an RPM of $49.26 against a baseline near $7.78, roughly six times normal. There was no traffic behind it: page views were among the lowest of the month and clicks were a bog-standard Monday. The entire delta was cost per click, and it moved across every ad unit at once.
| Unit | Cost per click, baseline | Cost per click, quarter-end |
|---|---|---|
| Anchor | $0.32 | $1.00 |
| Leaderboard | $0.62 | $1.98 |
| Site-wide RPM | $7.78 | $49.26 6x |
Same traffic, same placements, roughly 3x the cost per click across every unit. Nothing on the site changed.
The proof it was market-wide
A topically unrelated health site we run spiked the exact same two days, its RPM going from a $3 to $4 baseline to $7.55 and then $14.62. Two sites with nothing in common, moving in lockstep, cannot be explained by anything either site did. That is the tell. When one site posts an anomalous RPM day, check a second site on the same dates before you attribute a cause. Same-day co-movement is an auction event with nothing to reproduce. Divergence is something you did, and worth reproducing.
Why it happens, and when to expect it
Those were the last two business days of the quarter. Advertisers on quarterly budgets bid up inventory to spend what is left before the clock resets, and cost per click jumps for everyone at once. Expect the same around the end of September and the end of December, where the year-end close stacks on top of the documented fourth-quarter lift that already runs 40 to 60 percent above the year's baseline.
The lever, and the one that isn't
The lever is not anything you do on the day. It is having your full inventory indexed and your ad coverage complete before the flush arrives, so the higher bids land on pages that are already earning. The mistake is the opposite: seeing a spike, changing your setup to chase it, and carrying that change into a normal week where it only costs you.
How we measured it
AdSense RPM and per-unit cost per click by day on two sites in our network across a quarter boundary, read against each site's own trailing baseline. RPM and CPC are ratios, so none of this is a revenue figure. The finding is that two unrelated sites moved together on a calendar date, which is the signature of an auction event and not of site performance.