Internalization and stock price clustering: Finnish evidence

Internalization, the practice of brokers executing trades in-house, is a significant phenomenon in the Helsinki Stock Exchange. During the continuous trading session, 97.5% upstairs market trades are internalized. The corresponding figure for after-hours upstairs market trades is 73.1%, The prices of internalized trades are somewhat more clustered than the prices of other trades during the continuous trading session, but they are not more clustered than the prices of negotiated trades in the after-hours upstairs market. This suggests that Finnish brokers do not use a more discrete set of prices for internalized trades than for other upstairs trades. (C) 2000 Elsevier Science Ltd. All rights reserved. JEL classification: D23; G18.