I don't think that's the economical definition of monopoly. It's not about 1 single actor owning the market but rather about unilateral change. Obviously a single actor owning 99.99% will be able to shape the market ... but also one owning a lot less, e.g. 30% if even if they don't collude with another actor owning e.g. 21%.

not nitpicking; huge difference between 0 and 1 competitor