Research Papers

A Profitable Day Trading Strategy For The U.S. Equity Market

Working Paper

The validity of day trading as a long-term consistent and uncorrelated source of income for traders and investors is a matter of debate. In this paper, we endeavored to answer this question by conducting a thorough analysis of the profitability of Opening Range Breakout (ORB) strategies, with a particular focus on the 5-minute ORB. Using a large dataset that covered more than 7,000 US stocks traded from 2016 to 2023, the research aimed to assess how effective this strategy was in producing consistent and uncorrelated returns. A new aspect of our study was the focus on Stocks in Play, which are stocks that show higher than normal trading activity on a specific day, mostly because of fundamental news about the company. Our results showed a significant benefit in limiting day trading only to those Stocks in Play (even after considering transaction costs). A portfolio that consisted of the top 20 Stocks in Play achieved a total net performance of over 1,600%, with a Sharpe ratio of 2.81, and an annualized alpha of 36%. Passive exposure in the S&P 500 would have achieved a total return of 198% during the same period. Furthermore, this paper expanded the analysis to compare the return profile of the ORB strategy applied to different time frames, such as 15, 30, and 60 minutes. In the last part of the paper, we presented detailed stock-specific statistics for the 25 best and worst performers of an ORB strategy over all the time frames. To the best of our knowledge, this is the first public paper with such intraday granularity and a comprehensive stock-level database.

Liquidity Provision to Leveraged ETFs and Equity Options Rebalancing Flows

Evidence from End-of-Day Stock Prices

Working Paper

Rebalancing of leveraged ETFs and delta-hedging of equity options are two distinct and economically significant sources of order flow and liquidity demands. We show that they induce significant end-of-day momentum and mean-reversion in stock returns, while the effects dissipate within the next trading day. While gamma effects are persistent throughout our sample, those stemming from leveraged ETFs are decreasing significantly over time. We argue that these dynamics arise from different intermediation structures, generating heterogeneous levels of information asymmetry on rebalancing flows. While leveraged ETF providers generate perfectly predictable flows because of their strict mandate, option delta-hedgers have flexibility in deciding the strategic timing of their rebalancing, resulting in less predictable flows. Consistent with this view, we find that leveraged ETF flows attract more liquidity provision and that their effect on prices is shorter-lived. Our findings suggest that information disclosure is beneficial for market liquidity.

On The Quality Of Cryptocurrency Markets

Centralized Versus Decentralized Exchanges

Working Paper

Despite the growing adoption of decentralized exchanges, little is known about their market quality. Using a novel and comprehensive dataset, we compare decentralized blockchain-based venues (DEXs) to centralized crypto exchanges (CEXs) by assessing two key aspects of market quality: price efficiency and market liquidity. We find that CEXs provide better market quality overall and identify the main friction dampening DEX efficiency as the high gas price stemming from proof-of-work blockchains. We propose and empirically validate a stylized model of DEX liquidity provision, linking trading volume, protocol fees, and liquidity in equilibrium. Our theory identifies the quantitative conditions needed for DEXs to overtake CEXs in the future.

Gamma Fragility

Asset Pricing Implications of Delta-Hedging

Working Paper

We document a link between large aggregate dealers' gamma imbalances and intraday momentum/reversal of stock returns, arising from the potential feedback effects of delta-hedging in derivative markets on the underlying market. This channel relies on limited liquidity of the underlying market, but it is distinct from information frictions (adverse selection and private information) and funding liquidity frictions (margin requirement shocks). We test our joint hypothesis using a large panel of equity options that we use to compute a proxy of stock-level gamma imbalance. We find supporting evidence that intra-day momentum (reversal) is explained by the interaction of negative (positive) ex-ante gamma imbalance and and illiquidity. The effect is stronger for the least liquid underlying securities. Our results help to explain both intra-day volatility and autocorrelation of returns. Moreover, we find that gamma imbalance is related to the frequency and the magnitude of flash crash events.

Focusing at High Frequency

An Attention-based Neural Network for Limit Order Books

Job Market Paper

Machine learning methods deliver superior forecasting accuracy but can hardly be used to make inference. To overcome this limitation, I propose an encoder-decoder neural network augmented with an attention-based mechanism that can autonomously learn to identify the most critical regions of the input data. I first train the model using high-frequency message data from the NASDAQ and show that it outperforms other state-of-the-art models in forecasting future transaction prices. Then, I develop a methodology that uses the attention mechanism to make inference on the relative share of information content of market orders versus limit orders, concluding that the most informative events are executions of market orders while submission and cancellations of limit orders are less relevant. Finally, I test the model's behavior during the execution of real block orders from institutional investors, showing that it favors liquidity provision rather than front-running strategies.

Brokers and Order Flow Leakage

Evidence from Fire Sales

Published in the Journal of Finance

Using trade-level data, we study whether brokers play a role in spreading order flow information. We focus on large portfolio liquidations, which result in temporary drops in stock prices, and identify the brokers that intermediate these trades. We show that these brokers’ best clients tend to predate on the liquidating funds: at the beginning of the fire sale, they sell their holdings in the liquidated stocks, to then cover their positions once asset prices start recovering. The predatory trades generate at least 50 basis points over ten days and cause the liquidation costs for the distressed fund to almost double. These results suggest a role of brokers in fostering predatory behavior and raise a red flag for regulators. Moreover, our findings highlight the trade-off between slow execution and potential information leakage in the decision of optimal trading speed.

Quantitative Easing and Equity Prices

Evidence from the ETF Program of the Bank of Japan

Published in the Review of Asset Pricing Studies

Since the introduction of its Quantitative and Qualitative Easing program in 2013, the Bank of Japan has been increasing its holdings of Japanese equity through large scale purchases of index-linked ETFs with the intention of lowering assets' risk premia. We exploit the cross-sectional heterogeneity of the shock to supply induced by the policy to identify a positive, sizeable and persistent impact on stock prices consistent with a portfolio balance channel. The evidence suggests that demand curves for stocks are downward sloping in the long-run. We estimate an increase of 22 basis points in aggregate market valuation per trillion Yen invested into the program, corresponding to a price elasticity of 1. We show that the purchases of ETFs tracking the price-weighted Nikkei 225 index generate significant pricing distortions relative to a value-weighted benchmark. Finally, we provide a rigorous framework to discuss the consequences of a potential exit strategy from QE.

Machine Learning Approach for Loop Unrolling

Factor Prediction in High Level Synthesis

Published in IEEE

High Level Synthesis development flows rely on user-defined directives to optimize the hardware implementation of digital circuits. Nevertheless, the most beneficial directive values are hard to predict, and exhaustive explorations are infeasible even for moderately complex designs. Focusing on the Loop Unrolling directive, we herein address this challenge by proposing a novel Machine Learning methodology, able to jointly forecast the optimal loop unrolling factors for all the loops in a target application. We showcase that our method results in a better prediction score (up to 63%) and a reduced convergence time compared to other state-of-the-art approaches. Our method achieves 90% of the speedup that can be obtained (with a perfect a-priori knowledge of optimal loop unrolling factors) when synthesizing the computational hotspots of each considered benchmark as hardware accelerators.