Decreased price clustering in FTSE100 futures contracts following a transfer from floor to electronic trading

The issues of price clustering and electronic trading have triggered important recent debates, and generated interest from regulators due to their potential implications for market quality, stability, and fairness. This paper brings together these issues by examining whether price‐clustering behavior differs following a transfer of futures contracts from open outcry trading to an electronic system. The results are unique in demonstrating a structural change in price clustering following the move to automated trading, with the level of price clustering dropping from around 98.5% of prices at even ticks under floor trading to approximately 75% under electronic trading. Such a change in pricing behavior amounts to a reduction in the effective tick size, and is an important factor in reducing observed bid‐ask spreads.