The authors examined the time-dependent decay of rank-order stability of self-esteem and tested whether stability asymptotically approaches zero or a nonzero value across long test-retest intervals. Their finds suggest that the stability of self-esteem is relatively large, even across very long periods, and that self-esteem is a trait-like characteristic.
Kuster, Farah & Orth, Ulrich. (2013). Personality and Social Psychology, 39, 677-60.