Medium-frequency trading (MFT) is systematic trading in which positions are held from a few minutes to a few days. It occupies the middle of the range of trading frequency, between high-frequency trading, where holding times are seconds or less, and low-frequency trading, where they run to weeks or months. The boundaries are informal and differ from firm to firm.
Strategies in this band include intraday and overnight statistical arbitrage, short-horizon reversal and momentum, and trading around scheduled news. Signals come from prices, volumes and order book data sampled over seconds to hours, not from single ticks. Firms need good data and automated execution but do not have to win races measured in microseconds, so the investment in speed is far lower than in high-frequency trading. The main constraint is transaction cost. Positions turn over often, and the expected gain per trade is small, so spreads, fees and market impact decide whether a strategy is viable.