Retek customers include Abercrombie & Fitch, Bhs, Gap, New Look, Dixons, FNAC, Ingram Micro and the US Postal Service.
SAP said the combination of Retek's product range, industry expertise and market presence will allow it to respond to retailers' needs.
The acquisition will also offer retailers a strong alternative to Oracle.
Analyst group AMR Research said the deal would boost the confidence of Retek users, given SAP's stability and strength, but warned, "Although company viability will no longer be a concern, SAP's plans for product integration could have a negative impact on retailer upgrade planning."
The analyst also urged users to be wary of SAP's future strategy around middleware for Retek products, as it could try to base the middleware around its own Netweaver architecture.
For existing SAP Retail customers, AMR warned that SAP would adapt its roadmap for demand intelligence and customer order management strategies to take on board the Retek family.
"Overlapping areas in merchandise management and retail planning will also need to be sorted out," said the analyst.