Random deflated risk models have been considered in recent literatures. In this paper, we investigate second-order tail behavior of the deflated risk X = RS under the assumptions of second-order regular variation on the survival functions of the risk R and the deflator S. Our findings are applied to approximation of Value at Risk, estimation of small tail probability under random deflation and tail asymptotics of aggregated deflated risk.The main contributions of this paper concern the second-order expansions of the tail probability of the deflated risk X = RS which are then illustrated by several examples. Our main findings are utilized for the formulations of three applications, namely approximation of Value-at-Risk, estimation of small tail probability of the deflated risk, and the derivation of the tail asymptotics of aggregated risk under deflation.The rest of this paper is organized as follows. Section 2 gives our main results under second-order regular variation conditions. Section 3 shows the efficiency of our second-order asymptotics through some illustrating examples. Section 4 is dedicated to three applications. The proofs of all results are relegated to Section 5. We conclude the paper with a short Appendix.
Main resultsWe start with the definitions and some properties of regular variation followed by our principal findings. A measurable function f : [0, ∞) → IR with constant sign near infinity is said to be of second-order regular variation with parameters α ∈ IR and ρ ≤ 0, denoted by f ∈ 2RV α,ρ , if there exists some function A with constant sign near infinity satisfying lim t→∞ A(t) = 0 such that for all x > 0 (cf. Bingham et al. (1987) and Resnick (2007))Here, A is referred to as the auxiliary function of f . Noting that (2.1) implies lim t→∞ f (tx)/f (t) = x α , i.e., f is regularly varying at infinity with index α ∈ IR, denoted by f ∈ RV α ; RV 0 is the class of slowly varying functions. When f is eventually positive, it is of second-order Π-variation with the second-order parameter ρ ≤ 0, denoted by f ∈ 2ERV 0,ρ , if there exist some functions a and A with constant sign near infinity and lim t→∞ A(t) = 0 such that for all x positive lim t→∞ f (tx)−f (t) a(t)