- 5.11 Acquired By Compass Diversified
- 50 Below Sales & Marketing Acquired By LeadVenture
- 50 Floor Acquired By AEA Investors
- 50 megawatts of solar photovoltaic projects Acquired By SunEdison
- 50 MW PV project Acquired By First Solar
- 50 State Security Service Acquired By U.S. Security Associates
- 500friends Acquired By Merkle
- 500px Acquisitions
- 501 Auctions Acquired By Community Brands Intermediate
- 509 Acquired By Polaris
- 510 Kardiac Devices Acquired By Keystone Heart
- 510 Madison Avenue in New York City Acquired By Boston Properties
- 5150 Whips Acquired By Tolemar
- 51job Acquisitions
- 51Talk Online Education Group Acquisitions
- 523 Capital Acquisitions
- 53 Billa Supermarkets Acquired By Carrefour SA
- 53central.com Acquired By Mebelkart Technologies Pvt.
- 540 Madison Avenue Acquired By Boston Properties
- 55 Institutional Partners Acquired By JPMorgan Chase
- 55+ Magazine Acquisitions
- 57 North AB Acquisitions
- 58.com Acquisitions
- 5D Invest B.V. Acquisitions
- 5D Robotics Acquisitions
- 5D Systemkonsult AB Acquired By Addnode Group AB
- 5IQ Acquired By Impact Tech
- 5Leaf Acquired By NewBridge Global Ventures
- 5min Media Acquired By AOL
- 5N Plus Acquisitions
- 5nine Software Acquired By Acronis
- 5NINES Global Holdings Acquired By ServerFarm
- 5one Marketing Limited Acquired By MasterCard
- 5Rocks Acquired By Tapjoy
- 5Sept Etiquette Acquired By Alliance Etiquettes SAS
- 5square Mergers and Acquisitions
- 5Star Bank Acquisitions
- 5Star Bank - Credit Card Portfolio Acquired By UMB Bank National Association
- 5th & Ocean Clothing Acquired By New Era Cap
- 5th Century Partners Mergers and Acquisitions
