The TRADE 52 | Page 47

[ M A R K E T R E V I E W | A L G O S ] HOW TO COMPARE YOUR ALGORITHMS How does one best measure an algorithm’s perfor- mance? By all accounts it is not always a simple task. Algorithm transaction cost analysis (TCA) has been criticised as a poor science and many believes that algorithm benchmarks are being abused by gaming practices that make individual algorithms look good. “The state of Algo TCA is pretty abysmal” says Henri Waelbroeck, director of research, Portware. “It measures performance to a benchmark—but the question is the performance of what? Orders are of- ten modified by portfolio managers or merged with other orders by the trading desk – without taking the stream of instructions into account TCA be- comes irrelevant.” The solution, says Waelbroeck, is to construct a re- alistic baseline price for blocks by tracking the stream of portfolio manager instructions and order merging requirements, then allocating results—the realised price against the baseline—back to portfolio manager orders to account for costs for each portfolio. Issue 52 TheTradeNews.com 47