Consumers have been more concerned about Facebook privacy than usual since the social network introduced “instant personalization.” And now it looks like advertisers might have a reason to be wary of Facebook policy changes as well.

According to a letter that Facebook sent out to advertisers late last week, brands that have been buying CPM ads on the network may soon find their campaigns becoming less effective.

AllFacebook has a copy of the letter, which reads in part:

“Among other ongoing improvements, we are refining our ads delivery
system to better reflect the goals of our advertisers. This change will
take place over the next few weeks and, assuming current bids remain
unchanged, will mean that:

  • CPC advertisers (advertisers who have chosen to bid
    “cost-per-click”) may receive more clicks.
  • CPM advertisers (advertisers who have chosen to bid “cost per
    thousand impressions”) will continue to receive impressions but may
    receive less clicks.”

One advertiser tells AllFacebook:

“This is a HUGE deal since I am getting CPM
clicks for about $0.40 by writing good ads, and CPC costs me almost
double.”

Paying for impressions can be better than purchasing click-throughs if brands are confident that their ad copy will bring in higher click-through per impression than most. But if Facebook repositions CPM ads in places that aren’t conducive to clicks, the savings would disappear.

As commenter Don
Synstelien

puts it on Silicon Alley Insider:

“I can’t think of any way that FB could do
what they are indicating within their current layout unless they swap
the CPM ads to the lowest placement on the totem pole of ads they have
on page.

If that is the case, they really are screwing buyers of CPM ads – being
lowest on page also indicates that users may not actually ever “see” the
ad even though the ad will be technically “loaded” on the page and
counted as an impression, perhaps even below the fold.”

CPM ads on Facebook also allow advertisers to take advantage of user demographic information, which can make ads more effective. If this feature gets added to CPL ads, it could increase their click-throughs in relation to CPM. But the change could simply close the door to a loophole many advertisers have enjoyed until now

As an AllFacebook commenter writes:

“Rats, they finally fixed it. Smart Facebook advertisers have always
stayed away from CPC because CPM was so much cheaper (if you know what
you’re doing). Disappointed that I will no longer be able to take
advantage of this strategy.”

Image: David Boyle