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system
buying puts without owning underlying
user
yes, it's completely normal to buy (and sell) puts and other options without holding the underlying.  however, every (us) brokerage i know of only permits this within a margin account.  i don't know why...probably a legal reason.  you don't actually have to use the margin in a margin account.  if you want to trade options, though, you will need a margin account.
assistant