his study empirically investigates the effect of implementation of SFAS No.131 on companies' information environments by assessing the effect of interim period financial reports. Especially, using Beaver's information content measures, it investigates the market's reaction to interim period financial reporting under SFAS No.131. The empirical results of the information content test show that the adoption of SFAS No.131 does not affect the market's reaction. For the volume reaction test, no difference was found in the reaction to the interim financial statement filing for both voluntary and nonvoluntary disclosers. This result gives evidence that the information content of the new requirements of interim financial reporting is not significantly different from that under the previous requirements.