The 100 wealthiest people on the planet added $44.5 billion to their collective net worth last week as the Standard & Poor’s 500 Index had its longest winning streak since 2004.

The 39-year-old Google (Nasdaq: GOOG) founders Sergey Brin and Larry Page added a combined $2.2 billion to their fortune as shares of the Mountain View, California-based company rose the most since 2011. The company reported profit on Wednesday that topped analysts’ estimates as advertisers boosted spending to reach consumers during the holiday season.

Brin and Page rank 25th and 27th in the world with net worths of about $22 billion, according to the Bloomberg Billionaires Index.

“There’s obviously a general positive momentum in equity and the tech sector, so Google is following suit,” said Russ Certo, a managing director at New York-based Brean Capital LLC, in a telephone interview. “What’s driving it is the holiday shopping season. It was quite beneficial to Google, as their profit was more than any period since they went public in 2004.”

U.S. stocks rose, sending the S&P 500 to its first eight- day rally since 2004, as earnings beat estimates at 10 of 13 companies that reported results since the close of markets yesterday. Per-share profit has exceeded the average analyst estimate at about 76 percent of the 147 companies in the index that released results so far in the reporting season, according to data compiled by Bloomberg.

The S&P 500 gained 1.14 percent during the week to close at 1502.96 in New York. The Stoxx Europe 600 Index rose 0.94 percent, closing at 289.72

Slim, Buffett

Mexican telecommunications magnate Carlos Slim, 72, remains the richest person in the world, with a fortune of $78.3 billion, up $730 million for the week. Microsoft co-founder Bill Gates, 57, is second with a net worth of $64.3 billion. The Redmond, Washington-based firm reported lower profit on higher revenue Thursday, after the company spent more money to market its Windows operating system and lure consumers flocking to tablets and smart phones.

The world’s largest software maker is also planning to provide part of the financing for a leveraged buyout of Dell Inc. with Silver Lake Management LLC.

Europe’s richest man, Amancio Ortega, the 76-year-old founder of Inditex SA, the world’s biggest clothing retailer and owner of the Zara clothing chain, is No. 3 on the index with a net worth of $59.6 billion, $7.1 billion ahead of Warren Buffett, 82.

Icahn Feud

Billionaire Carl Icahn, reviving a decade-old feud with hedge-fund manager William Ackman, said the founder of Pershing Square Capital Management LP is taking “inordinate” risks in a wager against Herbalife Ltd. disclosed last year.

The 76-year-old, who spent more than seven years wrangling with Ackman in court over $4.5 million, said in an interview on Bloomberg TV Thursday that Ackman’s assertion he was shining a spotlight on Herbalife, the marketer of weight-loss and nutritional supplements, was “disingenuous.” Icahn ranks 38th on the index with a net worth of $19.5 billion.

Bloomberg.com recently unveiled the ranking with transparent net worth calculations and data visualization. The Bloomberg Billionaires Index takes measure of the world’s wealthiest people based on market and economic changes and Bloomberg News reporting. Each net worth figure is updated every business day at 5:30 p.m. in New York. The valuations are listed in U.S. dollars.