• New evidence on the price and liquidity effect of the FTSE100 index revisions.

      Mazouz, Khelifa; Saadouni, B. (2007)
      We study the price and liquidity effects following the FTSE 100 index revisions. We employ the standard GARCH(1,1) model to allow the residual variance of the single index model (SIM) to vary systematically over time and use a Kalman filter approach to model SIM coefficients as a random walk process. We show that the observed price effect depends on the abnormal return estimation methods. Specifically, the OLS-based abnormal returns indicate that the price effect associated with the index revision is temporary, whereas both SIM with random coefficients and GARCH(1,1) model suggest that both additions and deletions experience permanent price change. Added (removed) stocks exhibit permanent (temporary) change in trading volume and bid-ask spread. The analysis of the spread components suggests that the permanent change associated with additions is a result of non-information-related liquidity. We interpret the permanent price effect of additions and deletions combined with the permanent (temporary) shift in liquidity of added (removed) stocks as evidence in favour of the imperfect substitution hypothesis with some non-information-related liquidity effects in the case of additions.
    • The price effects of FTSE100 index revision: What drives the long-term abnormal return reversal?

      Mazouz, Khelifa; Saadouni, B. (2007)
      We examine short- and the long-term price effect associated with the FTSE 100 index revisions. We control for both heteroskedastic nature of the residual and the change, between the estimation and the test period, in the beta coefficient of the standard market model. Our findings reveal no relationship between the long-term price reversals and the change in the discount rate, as approximated by the beta coefficient of the market model. Overall, we provide strong evidence in favour of the price pressure hypothesis, where the price increase (decrease) gradually starting before the announcement an inclusion (exclusion) and reverses completely in less than two weeks after the index revision date.
    • Stabilization and the aftermarket prices of initial public offerings

      Mazouz, Khelifa; Agyei-Ampomah, S.; Saadouni, B.; Yin, S. (2012)
      The paper examines the determinants of stabilization and its impact on the aftermarket prices. We use a unique dataset to relax several assumptions in the stabilization literature. We find that underwriters support IPO prices shortly after listing, particularly in cold markets and when demand is weak. We also show that stabilized IPOs are more common amongst reputable underwriters. This finding suggests that stabilization may be used as a mechanism to protect the underwriter’s reputation. It also implies that reputable underwriters may possess private information and price IPOs closer to their true values (i.e., higher than those indicated by the weak premarket demand). Consistent with the latter view, we show that stabilized IPOs are offered at higher prices and suffer less underpricing than those indicated by the premarket demand, firm characteristics and market-wide conditions. The post-IPO performance results indicate that stabilized IPOs are unlikely to be mispriced as their prices do not exhibit any significant reversal after the initial stabilization period. We conclude that stabilization may be superior to underpricing as it protects investors from purchasing overpriced IPOs, benefits issuers by reducing the total money “left on the table” and enhances the overall profitability of underwriters.