Can an individual purchase and own stock in companies that compete against each other ?

Can an individual purchase and own stock in companies that compete against each other such as Kraft Inc, Kelloggs and General Mills or in this instance Coca Cola and Pepsico?
Update: Can an individual simultaneously purchase and own shares in companies that compete with each other such as Coca Cola and Pepsi or Microsoft and Apple?

P.S. Thank you for all your answers.
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