[Excerpt] This study examines the relation between the level of institutional investor ownership and the magnitude of security price variability at quarterly earnings announcement dates. Prior research consistently documents a negative association between firm size and announcement-date return variability. One explanation for this finding is that as more timely, alternative information becomes available on large firms prior to an announcement date, their security prices become informative, thereby reducing the information content of the earnings announcement. Large firms are closely followed by institutional investors. These investors dedicate substantial resources to information search. Therefore, the link between size and information production may be attributable to the influence of institutional investors on the information production process. Because institutional trades can also affect security prices, however, the precise impact of institutional following on the variability of prices at quarterly earnings dates is not evident.