An inverse tracker does not necessarily have the inverted long-term return as an equivalent non-inverted tracker.
Let's take two tracker, N and I. N is a "normal" tracker and I is an inverse tracker of index X. All three start at a value of 100.
On Day 1, X goes up 10% to 110. N also goes up to 100, and I goes down to 90 (-10%).
On day 2, X goes ...