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db.collection.aggregate({"$sort":{"year":-1}},{$group:{_id:{"stock":"$stock","year":"$year"},stockYearItems:{$push:"$$ROOT"}}},{$group:{_id:"$_id.stock",items:{$first:"$$ROOT"}}},{$unwind:"$items.stockYearItems"},{"$replaceRoot":{"newRoot":"$items.stockYearItems"}})