We examine whether a three-regime model that allows for dormant, explosive and collapsing speculative behaviour can explain the dynamics of the S&P 500. We extend existing models of speculative behaviour by including a third regime that allows a bubble to grow at a steady rate, and propose abnormal volume as an indicator of the probable time of bubble collapse. We also examine the financial usefulness of the three-regime model by studying a trading rule formed using inferences from it, whose use leads to higher Sharpe ratios and end of period wealth than from employing existing models or a buy-and-hold strategy. Copyright 2005 Royal Economic Society.

This study tests for the presence of periodically, partially collapsing speculative bubbles in the sector indices of the S&P 500 using a regime-switching approach. We also employ an augmented model that includes trading volume as a technical indicator to improve the ability of the model to time bubble collapses and to better capture the temporal variations in returns. We find that well over half of the S&P 500 index by market capitalization and seven of its ten sector component indices exhibited at least some bubble-like behavior over our sample period. Thus the speculative bubble that grew in the 1990s and subsequently collapsed was surprisingly pervasive in the US equity market and it affected numerous sectors including financials and general industrials, rather than being confined to information technology, telecommunications and the media. In addition, we develop a joint model for cross-sectional contagion of bubbles across the sectors and we examine whether there is evidence for bubble spillovers.

Article Accepted VersionBrooks, C. and Katsaris, A. (2005) Trading rules from forecasting the collapse of speculative bubbles for the S&P 500 composite index. AbstractMany recent studies have documented the presence of speculative bubbles, defined as systematic and increasing deviations of actual prices from fundamentals, in asset prices. However, thus far the usefulness of such models has been examined in the literature only from a statistical perspective. In this paper we employ two-regime switching models of periodically partially collapsing speculative bubbles and examine the risk-adjusted profits of trading rules formed using inferences from them. Use of trading rules derived from an augmented model incorporating market volume leads to higher risk adjusted returns than those obtained from employing existing models or from a buy and hold strategy.