Imagine the spot price of a non deliverable and not paying dividend asset is 100\$. With positive rate, the theoretical formula $F = S \cdot e^{rT}$ give us a future price higher, let's say 105.
If rate become negative before maturity, does the future price will 'cross' the spot price of the underlying asset? Because with negative $r$, $F$ will be reduce and could be lower than $S$, so at some point will there be a 'cross' of the two prices?