Three weeks after Hariri's March 14 alliance clinched 71 out of parliament's 128 seats in the June 7 poll, President Michel Sleiman tasked Hariri with forming a new government.
The Saudi-born Hariri initially attributed his political success to the sympathy vote for his father and five-time ex-premier, who founded the moderate Future movement that his 39-year-old son now leads.
Already a success of his own in the business world, Hariri was chosen to continue the "national and political mission" of his father, who was credited with rebuilding Lebanon after the devastating 1975-1990 civil war.
Forbes magazine put Saad Hariri's net worth at 1.4 billion dollars in its 2009 list of the world's billionaires, down from 3.3 billion last year.
Sources close to the family say they tapped Saad for a political role because he has more charisma and is better at interacting with people than his eldest brother, Bahaa.
While detractors derided him for his lack of political savvy and public speaking four years ago, Hariri has since emerged as a tranquil powerbroker to be reckoned with and a popular leader of Lebanon's Sunni Muslims.
Lebanon's Daily Star once labelled him an "unlikely" candidate whose "inexperience in walking the crooked paths of the Lebanese political environment is not a detriment but rather an asset."
Hariri was one of the main negotiators in the formation of the unity government in May 2008, bringing to an end a political crisis that had brought Lebanon to the brink of civil war.
While Hezbollah and its allies want to maintain the status quo, Hariri had said prior to the election that he would only accept another unity government if the Hezbollah alliance surrenders its veto powers.
Hariri is a business graduate of Georgetown University in Washington, and heads his late father's Saudi-based construction firm, Saudi Oger. One of the largest companies in the Middle East, it employs around 35,000 people.
The Hariri empire, which Saad has managed since 1996, also spans banking, real estate and media through companies such as Saudi Investment Bank, Saudi Research and Marketing Group and Future Television.
He also has his own real estate company.
Saad Hariri, who also holds Saudi nationality, was born April 18, 1970, Rafiq Hariri's second son by his first Iraqi wife.
He is married to Lara Bashir al-Adem, who hails from a prestigious Syrian family, and the couple have three children.
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