Elon Musk bought a 9.2% stake in Twitter, amounting to $2.9 billion.
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The 21st Commonwealth Games officially began on the Gold Coast, Queensland, Australia.
Finland officially joined NATO, becoming the 31st member of the security alliance.
Adolf Hitler formed the Schutzstaffel, the infamous paramilitary organization known to most as the SS.
New York City's Twin Tower World Trade Center was officially opened.
Martin Luther King Jr. was assassinated.
