Why cannot directly invest in a VIX?

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What’s the underlying asset?

It’s just an indicator.

Because it isn’t anything tangible.

VIX is calculated as the standard deviation of implied volatility as measured by the put/call ratio on SPY.

So, it has no dollar value.

That’s a weird way of saying it. Implied volatility _ is _ the standard deviation.

Sort of like saying it’s the color of a color.