We study price formation in securities markets, using the sequential trade framework of Glosten and Milgrom. This paper makes one basic methodological advance over previous research on sequential securities trading: we allow for multiple trade sizes for traders to choose from in a multi-period...

This paper studies how the trade size and the historical sequence of trades affect bid-ask spreads, investors’ trading strategies, and the market maker’s learning process in a multi-period economy. First, we show that there is a nonzero cut-off size below which informed traders never buy or...