Andreas Park

Herding and Contrarian Behavior in Financial Markets

Rational herd behavior and informationally efficient security prices have long been considered to be mutually exclusive but for exceptional cases. In this paper we describe the conditions on the underlying information structure that are necessary and sufficient for informational herding and contrarianism. In a standard sequential security trading model, subject to sufficient noise trading, people herd if and only if, loosely, their information is sufficiently dispersed so that they consider extreme outcomes more likely than moderate ones. Likewise, people act as contrarians if and only if their information leads them to concentrate on middle values. Both herding and contrarianism generate more volatile prices, and they lower liquidity. They are also resilient phenomena, although by themselves herding trades are self enforcing whereas contrarian trades are self-defeating. We complete the characterization by providing conditions for the absence of herding and contrarianism.

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.

Dark Trading on Public Exchanges

Over the last decade, market participants increasingly use trading tools that allow them to hide their trading intentions. We study how “dark trading” in the form of fully hidden, or dark, orders posted on a visible exchange affects the quality of the visible market. Dark orders were introduced on the Toronto Stock Exchange in 2011 in two stages, allowing us to employ a difference-in-differences approach to isolate the causal effect of the availability of dark trading. Using order-level data, we observe that the introduction of dark orders led to a widening of quoted spreads and an increase in trading costs, leaving depth, volume, and volatility unaffected. At the intra-day level, dark trading leads to decreased quoted spreads, increased depth, increased volume and to reduced trading costs and volatility. We interpret our findings as two sides of the same coin: the possible presence of dark liquidity causes market participants to post visible quotes more carefully. Upon detecting dark executions, however, traders infer that dark liquidity is diminished and thus post quotes more aggressively.

Herding and Contrarian Behavior in Financial Markets - An Experimental Analysis

We analyze and confirm the existence and extent of rational informational herding and rational informational contrarianism in a financial market experiment, and compare and contrast these with equivalent irrational phenomena. In our study, subjects generally behave according to benchmark rationality. Traders who should herd or be contrarian in theory are the significant sources of both within the data. Correcting for subjects who can be identified as less rational increases our ability to predict herding or contrarian behavior considerably.

How Syndicate Short Sales Affect the Informational Efficiency of IPO Prices and Underpricing

When a company goes public, it is standard practice that the underwriting syndicate allocates more shares than are issued. The underwriter thus holds a short position that it commonly fills by aftermarket trading when market prices fall or, when prices rise, by executing the so-called overallotment option. This option is a standard feature of initial public offering (IPO) arrangements that allows the underwriter to purchase more shares from the issuer at the original offer price. We propose a theoretical model to study the implications of this combination of short position and overallotment option on the pricing of the IPO. Maximizing the sum of both the profits from their share of the offer revenue and the potential profits from aftermarket trading, we show that underwriters strategically distort the offer price. This results either in exacerbated underpricing when favorably informed underwriters lower prices to secure a signaling benefit, or in informationally inefficient offer prices when underwriters pool in offer prices irrespective of their information.

Experiential Learning of the Efficient Market Hypothesis: Two Trading Games.

In goods markets, an equilibrium price balances demand and supply. In a financial market, an equilibrium price also aggregates peoples information to reveal the true value of a financial security. Although the underlying idea of informationally efficient markets is one of the centerpieces of capital market theory, students often have difficulties in grasping and accepting that asset prices fulfill this dual role of information revelation and demand-supply aggregation. The author presents two simple classroom games that illustrate the workings of information transmission and aggregation through prices. The games are easy to comprehend, simple to implement, and short. Each game, including classroom discussions, takes about 30 minutes. By the end, students will have an intuitive feel for informational efficiency.

Rushes in Large Timing Games

We develop a continuum player timing game that subsumes standard wars of attrition and pre‐emption games, and introduces a new rushes phenomenon. Payoffs are continuous and single‐peaked functions of the stopping time and stopping quantile. We show that if payoffs are hump‐shaped in the quantile, then a sudden “rush” of players stops in any Nash or subgame perfect equilibrium. Fear relaxes the first mover advantage in pre‐emption games, asking that the least quantile beat the average; greed relaxes the last mover advantage in wars of attrition, asking just that the last quantile payoff exceed the average. With greed, play is inefficiently late: an accelerating war of attrition starting at optimal time, followed by a rush. With fear, play is inefficiently early: a slowing pre‐emption game, ending at the optimal time, preceded by a rush. The theory predicts the length, duration, and intensity of stopping, and the size and timing of rushes, and offers insights for many common timing games.

Greed, Fear, and Rushes

We develop a simple new timing game that offers a unified theor y of sudden mass movements in economics, such as arise in matching, asset bubbles, and bank runs. We distinguish between rushes precipitated by greed and fear — i.e., the hunger for greater rewards from outlasting others, and the fear of missing out on early rewards. In our continuum player game, a payoff-relevant fundamental first “ripens”, peaks at a “harvest time”, and then “rots”. Payoffs are also scaled by a single-peaked quantile rank reward. Three local timing games arise in equilibrium: a war of attrition, a slow pre-emption game, and a pre-emptive rush. Our theory explains why matching rushes and bank runs happen inefficiently early, and asset sales rushes occur lat e. For with greed, the harvest time precedes an accelerating war of attrition ending in a rush, whereas with fear, an inefficiently early rush precedes a slowing pre-emption game ending at the harvest time. The theory yields consistent predictions for rush size, timing, gradual play timing, duration, and stopping rates. By our theory: (a) asset sales rushes reflect liquidity and relative compensat ion; (b) “unraveling” in matching markets depends on early matching stigma and market thinness; (c) illiquid bank loans yields complete bank runs before incomplete ones.

Regulating Dark Trading: Order Flow Segmentation and Market Quality

We examine the impact of a rule in the Canadian equities market that requires dark orders to offer price improvement over displayed orders. We show that this rule eliminated intermediation of retail orders in the dark and shifted retail orders onto the lit market with the lowest trading fee. Intermediaries shifted liquidity supply to this market leading to increased displayed liquidity. We conclude that reducing retail order segmentation enhances lit liquidity. Despite the improvement in liquidity, retail traders receive less price improvement; retail brokers pay higher trading fees to exchanges, and high frequency traders earn higher revenues from trading fees.

Taxing High Frequency Market Making: Who Pays the Bill?

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.