  The tick size, which is the smallest increment between two consecutive prices
for a given asset, is a key parameter of market microstructure. In particular,
the behavior of high frequency market makers is highly related to its value. We
take the point of view of an exchange and investigate the relevance of having
different tick sizes on the bid and ask sides of the order book. Using an
approach based on the model with uncertainty zones, we show that when
side-specific tick sizes are suitably chosen, it enables the exchange to
improve the quality of liquidity provision.
