MediaPost took at look at how cost per click rates seem to be bouncing up and down.  Depending on which search engine clients advertised on, resulted in very different pricing and pricing trends.

From the article:

Marketers in the Americas supported by Covario spent 9% more in Q4 2013 on campaigns, and 17% sequentially. Global CPC prices rose 10% compared with the year-ago quarter, but fell sequentially among the agency’s clients, mostly multinational high-tech brands.

Several factors forced CPCs to rise and fall depending on the search engine, region and industry. On Google in the United States, CPCs rose 10% in the quarter; and on the Yahoo Bing network CPCs fell 6% compared with the year-ago quarter, per Covario. Notably, the effectiveness of the ads — as measured through click-through rates (CTRs) — performed 28% better compared with the same quarter a year ago.

Covario analyst Alex Funk believes several factors led to unstable CPCs during the quarter. He points to an increase in mobile advertising that caused smartphone CPCs to fall 47% lower than desktop, mid-year updates to algorithms on Google Enhanced Campaigns, and increased investments in product listing ads (PLAs).

Read the whole story on MediaPost