Is the sentence "How much were your shares diluted?" correct?

Is the sentence "How much were your shares diluted?" correct?

Should it be "How much were your shares diluted to"?

They're both correct. And so is

How much were your shares diluted by?

Incidentally, the answer to

How much were your shares diluted?

would be My shares were diluted to 40% of their original value. or My shares were diluted by 60%. Simply giving a quantity would be ambiguous.

In contrast, the answers to

How much were your shares diluted by?

and

How much were your shares diluted to?

could be answered with a quantity (like 60%, for example) without any ambiguity.