Using a novel dataset where all traders are identifiable, we examine trading in the shares of a major company on the London Stock Exchange before 1920. Our main finding is that bid-ask spreads increased in the presence of informed trades. However, we also find that spreads narrowed during...

Short lived arbitrage opportunities arise when prices adjust with a lag to new information. They are toxic because they expose dealers to the risk of trading at stale quotes. Hence, theory implies that more frequent toxic arbitrage opportunities and a faster arbitrageurs' response to these...