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system
how to record short premium in double-entry accounting?
user
you don't. no one uses vanilla double entry accounting software for "held-for-trading security".  your broker or trading software is responsible for providing month-end statement of changes.  you use "mark to market" valuation at the end of each month.  for example, if your cash position is -$5000 and stock position is +$10000, all you do is write-up/down the account value to $5000.  there should be no sub-accounts for your "investment" account in gnucash.  so at the end of the month, there would be the following entries:
assistant