
#1 Carlos Slim Helu
$53.5 billion
Telecom, Mexico.
Telecom tycoon who pounced on privatization of Mexico's national telephone company in the 1990s becomes world's richest person for first time after coming in third place last year. Net worth up $18.5 billion in a year. Recently received regulatory approval to merge his fixed-line assets into American Movil, Latin America's biggest mobile phone company.

#2 Bill Gates
  $53 billion
 Microsoft, U.S.
 Software visionary is now the world's second-richest man. Net worth  still up $13 billion in a year as Microsoft shares rose 50% in 12  months, value of investment vehicle Cascade swelled. More than 60% of  fortune held outside Microsoft; investments include Four Seasons hotels,  Televisa, Auto Nation. Stepped down from day-to-day duties at Microsoft  in 2008 to focus on philanthropy.

#3 Warren Buffett
  $47 billion
 Investments, U.S. 
 America's favorite investor up $10 billion in past 12 months on  surging Berkshire Hathaway shares; says U.S. has survived economic  "Pearl Harbor," but warns recovery will be slow. Shrewdly invested $5  billion in Goldman Sachs and $3 billion in General Electric amid 2008  market collapse. Recently acquired railroad giant Burlington Northern  Santa Fe for $26 billion.

#4 Mukesh Ambani
  $29 billion
 Petrochemicals, oil and gas. India.
 Global ambitions: His Reliance Industries, already India's most  valuable company, recently bid $2 billion for 65% stake in troubled  Canadian oil sands outfit Value Creations. Firm's $14.5 billion offer to  buy bankrupt petrochemicals maker LyondellBasell was rejected. Since  September company has sold Treasury shares worth $2 billion to be used  for acquisitions. Late father, Dhirubhai, founded Reliance and built it  into a massive conglomerate.

#5 Lakshmi Mittal
  $28.7 billion
 Steel, India.
 London's richest resident oversees ArcelorMittal, world's largest  steel maker. Net profits fell 75% in 2009. Mittal took 12% pay cut but  improved outlook pushed stock up one-third in past year. Looking to  expand in his native India; wants to build steel mills in Jharkhad and  Orissa but has not received government approval. Earned $1.1 billion for  selling his interest in a Kazakh refinery in December.
 #6 Lawrence Ellison
#6 Lawrence Ellison$28 billion
 Oracle, U.S.
 Oracle founder's fortune continues to soar; shares up 70% in past 12  months. Database giant has bought 57 companies in the past five years.  Completed $7.4 billion buyout of Sun Microsystems in January; acquired  BEA Systems for $8.5 billion in 2008. Studied physics at U. of Chicago;  didn't graduate. Started Oracle 1977; took public a day before Microsoft  in 1986.

#7 Bernard Arnault
  $27.5 billion
 Luxury goods, France.
 Bling is back, helping fashion icon grab title of richest European as  shares of his luxury goods outfit LVMH--maker of Louis Vuitton, Moet  & Chandon--surge 57%. LVMH is developing upscale Shanghai commercial  property, L'Avenue Shanghai, with Macau billionaire Stanley Ho.

#8 Eike Batista
  $27 billion
 Mining, oil. Brazil.
 Vowing to become world's richest man--and he may be on his way. This  year's biggest gainer added $19.5 billion to his personal balance sheet.  Son of Brazil's revered former mining minister who presided over mining  giant Companhia Vale do Rio Doce got his start in gold trading and  mining.
 #9 Amancio Ortega
#9 Amancio Ortega$25 billion
 Fashion retail, Spain.
 Style maven lords over Inditex; fashion firm, which operates under  several brand names including Zara, Massimo Dutti and Stradivarius, has  4,500 stores in 73 countries including new spots in Mexico and Syria.  Set up joint venture with Tata Group subsidiary to enter India in 2010.  Betting on Florida real estate: bought Coral Gables office tower that is  currently home to Bacardi USA.

#10 Karl Albrecht
  $23.5 billion
 Supermarkets, Germany.
 Owns discount supermarket giant Aldi Sud, one of Germany's (and  Europe's) dominant grocers. Has 1,000 stores in U.S. across 29 states.  Estimated sales: $37 billion. Plans to open New York City store this  year. With younger brother, Theo, transformed mother's corner grocery  store into Aldi after World War II. Brothers split ownership in 1961;  Karl took the stores in southern Germany, plus the rights to the brand  in the U.K., Australia and the U.S. Theo got northern Germany and the  rest of Europe.