They raised their holdings over the past six weeks to 34,948,975 shares, more than five percent of Twitter's common stock, Alwaleed and Kingdom Holding, which he chairs, said in a joint statement.
Twitter shares closed Tuesday on the New York Stock Exchange at $27.62, giving the Alwaleed-Kingdom stake a market value of more than $965 million.
Alwaleed and Kingdom had already bought into Twitter in 2011, before the social media firm's 2013 initial public offering.
""This combined investment makes Prince Alwaleed and KHC the second largest shareholders in Twitter," it said."
As well as media stakes, Kingdom Holding's diversified interests range from the Euro Disney theme park to Four Seasons hotels and Citigroup.
Twitter, which has yet to turn a profit and is struggling to expand its user base above 300 million people, on Monday confirmed co-founder Jack Dorsey as its CEO.
Social media platforms such as Twitter are extremely popular in Saudi Arabia, a highly-conservative Muslim kingdom where official media are tightly controlled.
Al waleed influence on Twitter and his loyalty to Wahabi Kingdome may cause concerns for freedom in internet and keeping Privacy of users. Walid also has a good ties with west and now he is the 2nd stakeholder of the social site, still many people remember US’s NSA (National Security Agency) spying from American, European people and diplomat better to say, spying from the world.
So, more influence on this site meanse more accessibility to its content and information cooperation between saudis and allied intelligence servises. This matter in fact will endanger identities of opposition activist in Saudi and also spying from hostile country.
Al-Waleed Bin Talal bin Abdulaziz al Saud born 7 March 1954 is a member of the Saudi royal family.
He is a nephew of the late Saudi King Abdullah, a grandson of Ibn Saud, the first Saudi king, and a grandson of Riad Al Solh, Lebanon's first Prime Minister.