Bill Gates, the founder and chairman of Microsoft, has reclaimed the title of the world's richest man and increased his fortune by $15.8 billion in 2013.

According to the Bloomberg Billionaires Index, a daily ranking of the world's 300 richest individuals, the wealthiest people got even richer in 2013 and added $524 billion to their collective net worth.

At the market close on Tuesday, Dec. 31, 2013, the aggregate net worth of the world's top billionaires stood at $3.7 trillion. The biggest gainers came in the technology industry, which surged 28 percent in 2013. Out of the 300 people who appeared in the Bloomberg Billionaires Index, 70 people also registered a net loss for the 12-month period.

Shares of software giant Microsoft rose by around 40 percent in 2013. Gates owns around 4.5 percent of Microsoft and is currently the largest individual shareholder of the company. His fortune as of Dec. 31, 2013 was estimated to be $78.5 billion.

However, only less than a quarter of Gates' wealth is held in Microsoft shares. Gates holds stakes in around 35 public listed companies and also in several private firms, such as Four Season Hotels and Corbis Corp., a photo-archive company, via investment company Cascade Investments.

In 2013, Gates also benefited from increase in other stocks in his portfolio. Gates profited from his stakes in Canadian National Railway Company, whose share price went up by 34 percent in 2013. Gates also has stakes in hand sanitizer company Ecolab, whose share soared by 45 percent.

Gates also donates money towards charitable work. The billionaire has donated $28 billion to the Bill & Melinda Gates Foundation, an organization that tries to eradicate polio, malaria, AIDS and measles.

Global stocks surged in 2013 and the year witnessed the best annual gain since 2009, with the MSCI World Index increasing 24 percent during the year to close at 1,661.07 on December 31. The S&P's 500 Index also advanced 30 percent to close at 1,848.36, which is its best yearly gain since 1997. The Stoxx Europe also 600 gained 17 percent to close at 328.26.

Microsoft's share fell slightly by $0.25, or 0.67 percent, and closed at $36.91 per share on Friday, January 3. On Monday afternoon, the company's shares were trading 1.90 percent down at $36.21 on the Nasdaq.