Google is finally ready to split its stock for the first time, more than three years after co-founders Larry Page and Sergey Brin began discussing a move engineered to ensure they remain in control of the internet's most powerful company.

The split is scheduled to occur April 2. It had been delayed because of staunch resistance from other Google Inc. shareholders, who feared the manoeuvr would unfairly benefit Page and Brin at the expense of just about everyone else.

News of the split broke as Google reported fourth-quarter earnings rose 17 per cent, despite a long-running slump in its online ad revenue.

Google earned $3.4 billion, or $9.90 per share, in the October-December period. That compares with $2.9 billion, or $8.62 per share, in the prior year.

Excluding costs to cover employees' stock compensation, Google said it earned $12.01 per share. That was slightly below the average estimate of $12.22 per share among analysts polled by FactSet.

Revenue rose 17 per cent to $16.9 billion but Google is still struggling to close the gap between the rates for ads shown on mobile devices and those on personal computers.

Advertisers haven't been willing to pay as much to reach prospective customers on the smaller screens of smartphones and tablets, but Google Inc. has been tweaking its digital marketing system so mobile and PC ad campaigns are bundled together. In doing so, Google Inc. is hoping advertisers eventually will recognize the advantages of reaching people on the go and gradually begin to pay higher prices for mobile marketing pitches.

But Google's average ad price during the fourth quarter fell 11 per cent from the previous year. It was the ninth consecutive quarter that Google's average ad rate, also known as "cost per click," has fallen from the previous year.

Much of that erosion has been offset by more ads flowing into the system and Google's algorithms doing an even better job of showing the promotions to Web surfers mostly likely to be interested them. The total number of paid ad clicks increased by 31 per cent from the previous year.

"The demand was very strong, but the pricing is still not there on the mobile side," Edward Jones analyst Josh Olson said.

Google's stock is trading at $1,135, making it the most expensive in the market. It jumped 2.5 per cent in after-market trading after the earnings were released.

Google proposed the unorthodox stock split so that Page and Brin could preserve power in the company they started in a rented garage more than 15 years ago. It addresses concerns that the founders would lose control of Google as the company creates more shares to compensate its employees and buy startups.

To gain clearance for the split, Google settled a shareholders lawsuit and agreed to pay anywhere from roughly $300 million to $7.5 billion if the split doesn't pan out the way the Mountain View, Calif., company envisions.

Google's split creates a new class of "C" stock that carries no voting power. One share of C stock will be distributed for each share of Google's Class A stock, which provides its holders with a vote on corporate matters. Initially, the value of the current stock will be divided equally between the two types of shares. But they will then trade separately with different ticker symbols.

If the split hadn't been delayed by a legal skirmish, Google's stock probably wouldn't have exceeded $1,000 for the first time last fall.

Page and Brin primarily own Google's Class B stock, which already gives them 10 times the voting power of each Class A share. Combined, the Google founders control 56 per cent of the shareholder votes, even though they own less than 15 per cent of the outstanding stock.

Nonetheless, the voting clout of Page and Brin has been gradually shrinking, as Google has used Class A stock to reward employees and finance some of its acquisitions during the past decade.