Alphabet appears to have spooked investors with its fourth-quarter earnings report. The stock shed 3 percent immediately after the report and was in negative territory Tuesday morning before ending the day up close to 1 percent. The company on Monday beat Wall Street expectations on earnings and revenue. The figures aren't comparable to the fourth quarter of 2017, so it's hard to judge growth. But a beat on the top and bottom lines would normally send a stock up, not down. So here's what shareholders might have seen that they didn't like:

CPC

Cost per click on Google properties — the rough measure of what Alphabet charges advertisers for each ad served on its websites — dropped 29 percent from last year and 9 percent from last quarter. That's the steepest rate of annual decline in at least 16 quarters and suggests a growing threat from Amazon could be causing a pricing squeeze.

TAC

Alphabet paid $7.44 billion during the fourth quarter in traffic acquisition costs — the fees Google pays to companies like Apple to be the default search engine. That's an increase of 13 percent from the third quarter of this year and an increase of 15 percent from the year-ago quarter. TAC as a percent of advertising revenue, which investors would want to see shrinking, has held by 23 to 24 percent for the last six quarters.

Capital expenditures

Alphabet reported capital expenditures just north of $7 billion for the period, posting a much more expensive quarter than the $5.63 billion in capex that was projected. Full-year expenditures for the company spiked 90 percent to $25.14 billion, far outpacing full-year revenue growth of 23 percent. Spending in the company's Google segment more than doubled from the full year 2017.

Margin