Property Alliance Group is under offer to buy 55 Portland Street, a 70,000 sq ft office in Manchester city centre, while Credit Suisse has bought 44 Peter Street and 19 Spring Gardens from Magnus.
The 11-storey 55 Portland Street next to Manchester One is being sold by Royal London Asset Management. The former CIS Tower was previously occupied by Co-operative Insurance Society, now known as Co-operative Insurance.
Tenants include language school Alliance Francaise and recruitment company Economic Solutions.
Agents said the block could remain as offices and be refurbished, or could be converted to residential or hotel uses.
Meanwhile Magnus, part of Karlin Real Estate, has sold the 25,000 sq ft 44 Peter Street and the 36,000 sq ft 19 Spring Gardens to Credit Suisse for around £20m, a yield of 6.2%.
Tenants at 44 Peter Street include Kennedy Solicitors, Griffith & Armour and Buck Consultants, while 19 Spring Gardens occupiers include Lockton Insurance, Clarke Willmott and The Re-Think Group.
All parties declined or were unavailable to comment.