The Impact of Changes in the FTSE 100 Index

This paper investigates FTSE 100 index membership changes, which are determined quarterly by market capitalization and should have no information content. Return reversal around index additions and deletions suggests that buying (selling) pressure moves prices temporarily away from equilibrium, consistent with short‐term downward sloping demand curves. In contrast to widely reported results for the S&P 500, there is no evidence of permanent price effects. Further results suggest that investor awareness and monitoring due to index membership do not explain the price effects. There is statistically significant anticipatory trading in stocks that just fail to be promoted to the FTSE 100.     

Market Reaction to Changes in the S&P SmallCap 600 Index

Firms added to (deleted from) the S&P 600 index experience a significant price increase (decrease) at announcement. Firms that newly enter (exit) the S&P universe experience a larger price increase (decrease) than firms that move between S&P indexes. Trading volumes are higher after the announcement and institutional ownership increases (decreases) following index additions (deletions). However, the price and volume effects are temporary and are fully reversed within 60 days, in contrast to the permanent effects reported for S&P 500 changes. Our results support the temporary price‐pressure hypothesis and are similar to results reported for Russell 2000 index changes.     

The impacts of index rebalancing and their implications: Some new evidence from Japan

This study investigates the Nikkei 225 rebalancing. Unlike those for changes in the S&P 500, the price effects are permanent for both additions and deletions despite significant price reversals around both the announcement and effective days. The permanent price effects are shown to be consistent with the imperfect substitute hypothesis. Furthermore, the ‘arbitrage game’, as documented for the S&P additions, is played with both the Nikkei 225 additions and deletions. Lastly, consistent with its higher popularity, the Nikkei 225 changes induce more pronounced price and volume effects, more arbitrage trading, but less long-term volume effects than the Nikkei 500 reshuffles.     

Leverage-based index revisions: The case of Dow Jones Islamic Market World Index

US firms added to the Dow Jones Islamic Market World Index, a leverage-based index, witness permanent positive price and liquidity effects, whereas excluded firms sustain negative price and liquidity effects but no decrease in the investor awareness. Included/excluded firms experience a significant drop/no change in the cost of equity. Among the deleted firms, those with an increase in debt level bear a more severe decrease in liquidity and institutional ownership, and an increased cost of equity than those firms without an increase in debt use. Conveying private information on changes in a firm's corporate strategy and operating environment, revisions by a leverage-based index are different from those by size-based indexes.     

The liquidity effects associated with addition of a stock to the S&P 500 index: evidence from bid/ask spreads

This study examines changes in stock liquidity, as measured by the bid/ask spread, when a stock is added to the S&P 500 Index. The paper presents evidence of a significant decrease in the bid/ask spread upon S&P 500 addition, however, this effect is limited to only those stocks that were not trading listed options. Further, the decrease in the bid/ask spread for nonoptioned stocks is accompanied by a significant and permanent increase in share price and trading volume. While optioned stocks experience a permanent increase in trading volume, they experience only a temporary increase in share price. The findings for optioned stocks support the hypothesis that the price and volume effects associated with S&P 500 addition derive from temporary price pressure. Findings pertaining to the nonoptioned stocks indicate that the price and volume effects associated with S&P addition reflect enhanced stock liquidity. The decrease in the bid/ask spread for nonoptioned stocks is attributed to informational efficiencies achieved via index arbitrage trading, and it is argued that this effect is mitigated for optioned stocks due to the pre-existence of arbitrage trading between the option and the underlying stock.     

Institutional Ownership and Changes in the S&P 500

Several recent articles have provided new evidence for the existence of price pressures by examining the price and volume effects associated with changes in the S&P 500. The present study extends this work by examining actual changes in institutional holdings following both additions to and deletions from the S&P 500. The results show that changes in institutional holdings in response to additions or deletions from the S&P 500 are positively correlated. In addition to providing further evidence for the existence of price pressure effects, the results also provide evidence of the very large institutional elasticities of demand for stock.     

MARKET EFFECTS OF CHANGES IN THE STANDARD & POOR'S 500 INDEX

This paper examines the impact on stock returns of changes in the Standard & Poor's (S&P) 500 index. S&P states that firms are not added to or deleted from the index for valuation reasons but rather to maintain or improve the index's representative character. Results from market response tests indicate that stocks added to (deleted from) the index since 1975 experience a significant positive (negative) announcement day excess return. No announcement effect occurs in S&P changes prior to 1976. These announcement effects may be explained by a price-pressure hypothesis or by an information effect. Results of tests conducted to isolate which of these phenomena is present are reported.     

Asymmetric stock price and liquidity responses to changes in the FTSE SmallCap index

We examine market reactions to changes in the FTSE SmallCap index membership, which are determined quarterly based on market capitalization and are free of information effects. Our main results are asymmetric price and liquidity responses between the firms that are shifted between FTSE indexes and the firms that are new to FTSE indexes. Firms promoted from a smaller-cap to a larger-cap FTSE index experience a permanent increase in stock price accompanied by improvements in liquidity. Similarly, firms demoted from a larger-cap to a smaller-cap FTSE index experience a permanent decrease in stock price accompanied by declines in liquidity. In contrast, firms added to the FTSE SmallCap index that were not previously in FTSE indexes show a transitory price gain and declines in liquidity. The results support the liquidity and price pressure hypotheses.     

New evidence on the price and liquidity effects of the FTSE 100 index revisions

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.     

Intraday Price Formation in U.S. Equity Index Markets

The market for U.S. equity indexes presently comprises floor‐traded index futures contracts, exchange‐traded funds (ETFs), electronically traded, small‐denomination futures contracts (E‐minis), and sector ETFs that decompose the S&P 500 index into component industry portfolios. This paper empirically investigates price discovery in this environment. For the S&P 500 and Nasdaq‐100 indexes, most of the price discovery occurs in the E‐mini market. For the S&P 400 MidCap index, price discovery is shared between the regular futures contract and the ETF. The S&P 500 ETF contributes markedly to price discovery in the sector ETFs, but there are only minor effects in the reverse direction.     

What’s in the news? The ambiguity of the information content of index reconstitutions in Germany

We analyze stock price behavior around reconstitutions of the German DAX index family from 1990 to 2013. The strong price run-up of added stocks in the 2 months preceding the announcement date remains robust until 2 months after the effective date (ED), and is fully reversed 5 months later. Conversely, stock prices of deleted firms are under pressure until 10 months after the ED. Unlike most previous studies, we find that outright entries and exits have temporary price effects, as do additions to and deletions from better-known indices; however, promotions and demotions related to lesser-known indices command permanent stock price responses. Rather surprisingly, deleted stocks consistently earn higher abnormal returns than added stocks in the 5-year post-event period. Specifically, the return differential levels out at 77.3%. We establish that this differential in permanent stock prices is attributable to differences in operating performance and media coverage. In practice, index reconstitutions do not appear to give unambiguous signals about the long-run investment appeal of affected firms. However, index fund managers not constrained by tracking error minimization would be better off holding deleted stocks for 5 years after the ED.     

Retail investor attention and herding behavior

In this paper, we argue that when individual investors can obtain information from public resources such as Google search, the degree of investor attention to a particular underlying company is positively linked with herding behavior for retail investors. Empirical results confirm that Google Search Volume Index can be a proxy for the information demand of uninformed individual investors. Empirical evidence also shows that reaching the price limit generates an attention-grabbing effect. Further, in general, small cap firms generate more intensive individual investor herding. In addition, we explore the asymmetric impact of abnormal search volume index on individual investor herding behavior for bull and bear markets, and confirm that the individual investor buy herding phenomenon is stronger in bull markets, especially for small capitalization firms. In bear markets, with greater price deterioration for large cap firms, we detect herding behavior on the sell side.     

What's in the News? Information Content of S&P 500 Additions

I investigate the information content of S&P 500 index changes by examining the price and volume reaction of the industry and size matched firms. Using a sample of S&P 500 additions between 1976–2001, I find a significantly positive price reaction, but no volume reaction, for the matching firms. In addition, the matching-firm price reaction is negatively related to the added firm's weight in its industry. These findings suggest that the index addition conveys favorable information about the added firm and its industry.     

The Influence of Information Arrival on Market Microstructure: Evidence from Three Related Markets

This study examines the influence of information arrival on market microstructure for the MMI, NYSE, and S&P 500 stock index futures markets, with special emphasis on the effects of opening and closing of trading and expiration of contracts on price movements and trading activities. The results of the examination show that although the opening of the (MMI) futures market is associated with higher volatility, it is when the spot market opens that volatility reaches its highest level. Similarly, the closing of the futures markets, though more volatile, is not as volatile as the closing of the spot markets. Trading patterns, on the other hand, are distinct from volatility. For MMI, trading declines consistently after the close of the spot market. In contrast, the NYSE and S&P 500 continue to trade and reach a peak at the close of the futures markets. Expiration effects are evidenced by the increase in volatility and trading near the closing of the MMI and the spillover to the NYSE and S&P 500. In sharp contrast, the expirations of the NYSE and S&P 500 are only assooiated with decrease in trading, suggesting that efforts to dampen volatility by changing expiration days from Friday to Thursday and shifting settlement price from Friday close to Friday open, have been successful.     

A re-examination of the index effect: Gambling on additions to and deletions from the S&P 500's ‘gold seal’

This study examines the abnormal returns, trading activity, volatility and long-term performance of stocks that were added to the S&P 500 index. By using a three-factor pricing model that allows for firm size and value characteristics as well as market risk, we are able to shed new light on the widely observed ‘index effect’. We find that the CAPM tends to overstate the performance of large firms and to understate the performance of small firms. We also find a transitory increase in trading volume between the announcement and a few days after the effective date. In terms of the firm's operating performance, we find a significant increase in earnings per share after inclusion, which combines with the stock price rise to leave the average price-earnings ratio largely unaltered. Examining a unique sample of deletions of international companies and replacements with US companies, we find that deleted stocks experienced a considerable and permanent fall in price, inconsistent with the Investor Recognition Hypothesis. The “seal” of S&P 500 index membership has very long-term effects and inclusion appears not to be an information-free event.     

Information content of sustainability index recomposition: A synthetic portfolio approach

A firm’s inclusion on the Dow Jones Sustainability Index (DJSI) signals its leadership in Environmental, Social, and Governance (ESG). We studied the effects of DJSI inclusion using data through 2021. For additions, we found significant positive pre-announcement effects, as well as persistence of positive abnormal returns. On deletions, we also saw positive abnormal returns, although significance reduced in later years. Our analysis demonstrated a stronger information role of DJSI inclusion for non-S&P 500 firms, which suggests that the DJSI is relatively more important for firms with lower investor recognition. We used a generalised synthetic control approach to estimate our results, which responds to the parallel trends critique of stock return event studies and provides robustness to industry shocks that are so important to ESG applications. Thus, this paper represents an important extension to our understanding of the value relevance of DJSI membership.     

A Likelihood Ratio Test of Price Volatilities: Comparing Stock Index Spot and Futures

This paper uses three methods to estimate the price volatility of two stock market indexes and their corresponding futures contracts. The classic variance measure of volatility is supplemented with two newer measures, derived from the Garman-Klass and Ball-Torous estimators. A likelihood ratio test is used to compare the classic variance measure of price volatilities of two stock market indexes and their corresponding futures contracts during the bull market of the 1980s. The stock market volatilities of the Standard & Poor's 500 (S&P 500) and New York Stock Exchange (NYSE) indexes were found to be significantly lower than their respective futures price volatilities. Since information may flow faster in the futures markets than in the corresponding stock market, our results support Ross's information-volatility hypothesis. It was also noted that the NYSE spot volatility was lower than the S&P 500 spot volatility. If the rate of information flow and firm size are positively related, then the lower NYSE spot volatility is explained by the size effect. The futures price volatilities for the two indexes were insignificantly different from each other. With stock index spot-futures price correlations approaching unity, one implication of our results for index futures activity is that smaller positions in futures contracts may suffice to achieve hedging or arbitrage goals.     

A comprehensive long-term analysis of S&P 500 index additions and deletions

We investigate the long-term effects of S&P 500 index additions and deletions on a sample of stocks from 1962 to 2003 and find a significant long-term price increase for both added and deleted stocks, with deleted stocks outperforming added stocks. The long-term price increase for added stocks can be attributed to increases in institutional ownership, liquidity, and analyst coverage, and a decrease in the shadow cost in the long-term. However, while deletion has no significant effect on analyst coverage and shadow cost, we find a rebound in the institutional ownership and liquidity of deleted stocks. The difference in the long-term price increase of added and deleted stocks can be explained by analyst coverage and operating performance.     

凤尾变鸡头:被忽视的指数成分股交换

沪深300和中证500同时调整成分股,沪深300调出的股票大部分会进入中证500。这些交换的成分股既有沪深300调出效应,也有中证500调入效应。已有文献专注于沪深300调出样本整体的调出效应,却忽视了交换股还有中证500调入效应。本文首先使用断点回归设计研究交换股,证明了指数效应在国内存在。随后,使用Fama-French五因子模型研究交换股与其它沪深300调出股的差异,解释了为何国内研究认为指数效应不存在:交换股主要表现出调入效应,抵消了其它沪深300调出股的调出效应,忽视指数成分股交换导致了整体调出效应“不显著”,甚至为正。     

Investor sentiment,SEO market timing,and stock price performance

This article details an investigation of the impact of investor sentiment on the probability of firms conducting seasoned equity offerings (SEOs) and on stock price performance around and subsequent to SEOs. The results show that investor sentiment has a positive impact on SEO probability and that this impact is stronger for small and young firms. Furthermore, firms conducting SEOs during high sentiment periods experience less severe short-run price drops around the issuance yet more severe post-issue long-run underperformance, compared with firms conducting SEOs during low sentiment periods. These effects of investor sentiment on stock price performance are stronger for small, young, and high market-to-book ratio firms.