Ryan Riordan

Algorithmic Trading and the Market for Liquidity

We examine the role of algorithmic traders (ATs) in liquidity supply and demand in the 30 Deutscher Aktien Index stocks on the Deutsche Boerse in Jan. 2008. ATs represent 52% of market order volume and 64% of nonmarketable limit order volume. ATs more actively monitor market liquidity than human traders. ATs consume liquidity when it is cheap (i.e., when the bid-ask quotes are narrow) and supply liquidity when it is expensive. When spreads are narrow ATs are less likely to submit new orders, less likely to cancel their orders, and more likely to initiate trades. ATs react more quickly to events and even more so when spreads are wide.

High-Frequency-Trading

High-frequency trading (HFT) has recently drawn massive public attention fuelled by the U.S. May 6, 2010 flash crash and the tremendous increases in trading volumes of HFT strategies. Indisputably, HFT is an important factor in markets that are driven by sophisticated technology on all layers of the trading value chain. However, discussions on this topic often lack sufficient and precise information. A remarkable gap between the results of academic research on HFT and its perceived impact on markets in the public, media and regulatory discussions can be observed.The research at hand aims to provide up-to-date background information on HFT. This includes definitions, drivers, strategies, academic research and current regulatory discussions. It analyzes HFT and thus contributes to the ongoing discussions by evaluating certain proposed regulatory measures, trying to offer new perspectives and deliver solution proposals.

Do Retail Traders Suffer from High Frequency Traders

In April 2012, the Canadian regulator IIROC imposed a fee on order submissions and cancellations. Worldwide, this was the first time that a regulator imposed a cost on activities that are intrinsic components of high frequency traders’ strategies. We find that high frequency market makers adjusted their behavior and acted significantly less competitively, so that market-wide bid-ask spreads rose by 9%, causing an increase in trading costs for retail traders. The implementation shortfall for institutions that used marketable orders increased, too, but for those that use both market and limit orders, costs remained unaffected. Our study provides causal evidence for the critical importance of liquidity provision by high frequency market makers in today’s markets.

High-Frequency Trading and Extreme Price Movements

Are endogenous liquidity providers (ELPs) reliable in times of market stress? We examine the activity of a common ELP type—high frequency traders (HFTs)—around extreme price movements (EPMs). We find that on average HFTs provide liquidity during EPMs by absorbing imbalances created by non-high frequency traders (nHFTs). Yet HFT liquidity provision is limited to EPMs in single stocks. When several stocks experience simultaneous EPMs, HFT liquidity demand dominates their supply. There is little evidence of HFTs causing EPMs.

High Frequency Trading and the 2008 Short Sale Ban

We examine the effects of high-frequency traders (HFTs) on liquidity using the September 2008 short sale-ban. To disentangle the separate impacts of short selling by HFTs and non-HFTs, we use an instrumental variables approach exploiting differences in the bans cross-sectional impact on HFTs and non-HFTs. Non-HFTs’ short selling improves liquidity, as measured by bid-ask spreads. HFTs’ short selling has the opposite effect by adversely selecting limit orders, which can decrease liquidity supplier competition and reduce trading by non-HFTs. The results highlight that some HFTs’ activities are harmful to liquidity during the extremely volatile short-sale ban period.

Do Multilateral Trading Facilities Contribute to Market Quality

The introduction of the Markets in Financial Instruments Directive (MiFID) ended the quasi-monopoly of traditional exchanges and enabled alternative platforms, so-called multilateral trading facilities (MTF), to compete for order flow. European regulation imposes neither a formal linkage nor a consolidated market record. This raises questions about the contribution to market quality of MTFs in an increasingly fragmented trading environment. We find that Chi-X, an MTF, contributes most to the price discovery process. Chi-X is competitive in liquidity supply and posts the tightest quoted spreads. Our results suggest that MTFs contribute positively to market quality and that investors benefit from competition.

Price Discovery Without Trading: Evidence from Limit Orders

We analyze the contribution to price discovery of market and limit orders by high‐frequency traders (HFTs) and non‐HFTs. While market orders have a larger individual price impact, limit orders are far more numerous. This results in price discovery occurring predominantly through limit orders. HFTs submit the bulk of limit orders and these limit orders provide most of the price discovery. Submissions of limit orders and their contribution to price discovery fall with volatility due to changes in HFTs’ behavior. Consistent with adverse selection arising from faster reactions to public information, HFTs’ informational advantage is partially explained by public information.

Price efficiency in futures and spot trading: The role of information technology

During the last years information technology has had a profound impact on financial markets. The speed of trading and the amount of available information has increased substantially. Nearly all exchanges have upgraded their trading systems to meet the demand of investors and enhance their competitive position. However, the impact on liquidity and price efficiency remains unclear. In this paper we present an event study to examine the effects of an infrastructure change at the Deutsche Borse in Germany. On April 23, 2007, Deutsche Borse released an upgraded version of their electronic trading system Xetra. We study the impact that this upgrade had on the efficiency of prices, measured as the pricing gaps between the observed futures prices and their theoretical values based on the underlying cash market. Our results suggest that the system upgrade reduced the pricing gapand thus improved price efficiency.

System Latency in Linked Spot and Futures Markets

We examine the lead-lag effect between DAX index and DAX index futures under asymmetric latency in the exchange infrastructure. Using 1-min high frequency observations in 2006-2007, it is found that the market integration between stock index and stock index futures has significantly grown compared to prior research. While the degree of price discovery in the futures market decreased both markets react mostly contemporaneously towards new information. An event story of latency reduction on Xetra reveals that exchange latency is one important factor explaining this development. We find evidence that smaller asymmetric round-trip-times between Xetra and Eurex lead to a higher degree of market integration.

Scarcity effects of QE: A transaction-level analysis in the Bund market

This paper investigates the scarcity effects of quantitative easing (QE) policies, drawing on intra-day transaction-level data for German government bonds, purchased under the Public Sector Purchase Program (PSPP) of the ECB/Eurosystem. This paper is the first to match high-frequency QE purchase data with high-frequency inter-dealer data. We find economically significant price impacts at high (minute-by-minute) and low (daily) frequencies, highlighting the relevance of scarcity effects in bond markets. Asset purchase policies are not without side effects, though, as the induced scarcity has an adverse impact on liquidity conditions as measured by bid-ask spreads and inter-dealer order book depth. We further show that the price impact varies greatly with market conditions: it is considerably higher during episodes of illiquidity and when yields are higher.