Expecting high growth, Saudi Prince Alwaleed Bin Talal and Kingdom Holding Company (KHC), the investment fund he largely owns, have put $300 million in Twitter.

A canny investor, the insanely rich prince, a nephew of Saudi King Abdullah, bought into Apple when it was down on its luck and the newly returned Steve Jobs was borrowing money from Microsoft to keep the lights on. He also bought into Citigroup, when the bank needed it, on a cold call from the Carlyle Group and owns a piece of General Motors.

The announcement Monday said the investment in Twitter was the "result of several months of negotiations and comprehensive due diligence." Described as a "strategic stake," it is thought to amount to 3.6% of the company based on an assumed valuation of $8.4 billion, but nobody knows.

The Wall Street Journal suggested that Talal may have gotten the stake from one of Twitter's co-founders. Fortune says it was Twitter insiders. Earlier this year the site, in no rush to go public, reportedly picked up $400 million financing from a group led by Russian VC Digital Sky Technologies. The paper says reports around then had Twitter looking for $800 million, which would bring the amount it's raised to about $1 billion. That of course depends on where the prince's shares came from.

KHC executive director of private equity and international investments Ahmed Halawani said in a statement, "We believe that social media will fundamentally change the media industry landscape in the coming years. Twitter will capture and monetize this positive trend."

Part of Twitter's attractions for the prince is believed to be the role that it has played in the Arab Spring uprising.

Arabic messaging is the fastest-growing segment on Twitter, according to Semiocast, up 2,146% in the 12 months ended October 31.

The microblogging site is now supposed to have more than 100 million active users producing 250 million tweets a day through the web, smartphones and the simplest of feature phones.

The prince's press release pointed out that he is heavily invested in Arab media through the Saudi Research and Marketing Group (SRMG), in which Kingdom Holding holds a 29.9% stake. The publications that fall under SRMG include Asharq Al Awsat, Al Eqtisadiah, Arab News, Hia magazine, Al Majalla magazine, Arrajol magazine and Sayidati magazine. It is also represented in Al Khaleejiya for Publicity Advertising and Public Relations and Al Madina Printing and Publishing Company.

KHC also owns roughly 7% of News Corp's Class B Common Stock and News Corp, of course, owns Dow Jones and the Wall Street Journal among other outlets.

The prince owns the Rotana Group, the Arab world's largest entertainment company, which recently sold a 9.09% piece to News Corp, and plans to launch his own privately owned Arabic-language Alarab satellite news channel with Bloomberg.