Mayer’s pay package is made up of $1 million in annual salary, as much as $2 million in an annual bonus, and $42 million in stock options and other awards, as well as $14 million in “make whole restricted options” for forfeiture of compensation from Google.

Also, by including some stock grants, Mayer could earn up to a total of $20 million a year, or up to $100 million over five years, a Yahoo spokeswoman told Reuters.

As the first female Google engineer and one of its earliest employees, Mayer’s net worth is already estimated to be as much as $300 million.

Yahoo’s hiring of Mayer as CEO from Google earlier this week caught analysts and investors by surprise. Mayer, 37, edged out presumed front-runner and acting CEO Ross Levinsohn to become Yahoo’s third CEO in a year.

Industry observers believe Mayer’s selection over Levinsohn is a signal that Yahoo is likely to renew its focus on Web technology and products rather than beefing up online content.

Her appointment caps a tumultuous year at Yahoo. In May, Scott Thompson resigned as CEO after less than six months in the job after a controversy over his academic credentials. Thompson replaced the controversial Carol Bartz, who was fired in September after failing to revitalise Yahoo.

Thompson’s total compensation at hire was valued at $27 million. He got no severance but was able to keep the $7 million in compensation he got for leaving Paypal. Bartz got more than $10 million in severance when she was fired last year.