# How spread changes affect the order book: Comparing the price responses of order deletions and placements to trades

## TL;DR

This paper investigates how different events like trades, deletions, and limit order placements influence the bid-ask spread and stock prices, revealing that deletions often widen the spread and have market impacts similar to trades.

## Contribution

It provides a comparative analysis of spread changes caused by trades, deletions, and placements, highlighting the significant role of deletions in market dynamics.

## Key findings

- Deletions open the bid-ask spread more often than trades.
- Spread changes due to deletions influence other order book observables.
- Price responses to deletions are similar to those caused by trades.

## Abstract

We observe the effects of the three different events that cause spread changes in the order book, namely trades, deletions and placement of limit orders. By looking at the frequencies of the relative amounts of price changing events, we discover that deletions of orders open the bid-ask spread of a stock more often than trades do. We see that once the amount of spread changes due to deletions exceeds the amount of the ones due to trades, other observables in the order book change as well. We then look at how these spread changing events affect the prices of stocks, by means of the price response. We not only see that the self-response of stocks is positive for both spread changing trades and deletions and negative for order placements, but also cross-response to other stocks and therefore the market as a whole. In addition, the self-response function of spread-changing trades is similar to that of all trades. This leads to the conclusion that spread changing deletions and order placements have a similar effect on the order book and stock prices over time as trades.