Abstract
In this paper we consider a heavy-tailed stochastic volatility model, Xt = σtZt, t ε ℤ, where the volatility sequence (σt) and the i.i.d. noise sequence (Zt) are assumed independent, (σt) is regularly varying with index α > 0, and the Zt's have moments of order larger than α. In the literature (see Ann. Appl. Probab. 8 (1998) 664-675, J. Appl. Probab. 38A (2001) 93-104, In Handbook of Financial Time Series (2009) 355-364 Springer), it is typically assumed that (logσt) is a Gaussian stationary sequence and the Zt's are regularly varying with some index α (i.e., (σt) has lighter tails than the Zt's), or that (Zt) is i.i.d. centered Gaussian. In these cases, we see that the sequence (Xt) does not exhibit extremal clustering. In contrast to this situation, under the conditions of this paper, both situations are possible; (Xt) may or may not have extremal clustering, depending on the clustering behavior of the σ -sequence.
Original language | English |
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Journal | Bernoulli |
Volume | 19 |
Issue number | 5A |
Pages (from-to) | 1688-1713 |
ISSN | 1350-7265 |
DOIs | |
Publication status | Published - 2013 |