Increased footfall makes it harder for staff to spot criminals, and items that are piled high and not properly tagged in the rush to stock the shelves.
Another problem is the failure to properly train temporary staff taken on for the festive season.
The study was commissioned by retail advisers Checkpoint Systems from loss preventer Ernie Deyle, which said: "Retailers are faced with the difficult task of managing the influx of customers, as well as protecting their merchandise."
Clothes, luxury foods and electronic accessories are likely to be the most stolen items this festive season.
The report suggests staff training, technology such as tags, "maintaining operational execution standards" and to "update planning and financial performance models to properly account for advanced deliveries of seasonal products".
Fung Global Retail & Technology suggested holiday spending could increase by 3.5 per cent year-on-year, up £2.5bn to £73bn in the UK in November/December.