Locate Costs versus Slippage

Here s a question from Oleg on short locate costs versus slippage in a backtest ( name used with permission, edited for clarity ): Oleg: Wouldn t accounting for HTB (hard-to-borrow) cost in a backtest be a bit different than slippage? We don t know how much they will be when the time to place a trade comes, but unlike slippage (outcome of which we find out only after the trade is placed), with HTB…