MDY may refer to:
- the calendar format "Month, Day, Year" (see Calendar date#Gregorian, month-day-year (MDY) and Date and time representation by country).
- the ticker symbol for MidCap SPDRs, an exchange-traded fund.
- MDY Industries, creator of the Glider bot software.
- the IATA airport code for Henderson Field (Midway Atoll).
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