Mainsail Management

What Mainsail Management does

Mainsail Management Inc. is a Boston-based real estate investment, development, and property management firm founded in 1981 and led by President Jim Keliher. The company focuses on luxury residential real estate across Greater Boston's most prestigious neighborhoods — Back Bay, Beacon Hill, South End, Bay Village, Brighton, Dorchester, and Brookline — and reports a track record of more than 125 condominium conversions over four decades. Its portfolio spans ultra-luxury condominiums (e.g., 142 Beacon Street, 117 Beacon Street, 67 St. Botolph Street, 476 Beacon Street), single-family residences (170 West Brookline Street, 11 Melrose Street), a 62-unit new-construction condominium project at 99 Tremont Street developed in joint venture with Saracen Properties, a growing rental apartment portfolio (69 Bailey Street, plus legacy buildings), and design collaborations with firms such as Grassi Design Group and IDF Studios.

The business operates on three revenue streams: one-time real estate development and sale of luxury units, recurring property management fees for residential and commercial assets, and in-house construction services led by Head of Construction Tom Helms that handle gut renovations of historic brownstones and capital improvements. Distribution is direct — sales are conducted from the firm's headquarters at 251 Newbury Street in Boston's Back Bay, with marketing supported by a company website, a project blog, Instagram, and LinkedIn. The firm is privately held, founder-controlled, and employs 11-50 people, with no disclosed outside equity, AI/technology stack, patents, certifications, or public financial filings.

Name

Mainsail Management

Legal name

Mainsail Management Inc.

Website

https://mainsailmgmt.com

Company type

Private

Founded year

1981

Operating status

Operating

Headcount range

11–50 employees

Short description

Mainsail Management is a Boston-based real estate development and property management firm founded in 1981, specializing in luxury condominiums, single-family residences, and rental properties across Greater Boston, serving high-net-worth buyers and long-tenured private investor partners.

Ownership category

akta.pro rank

Product category

Luxury Real Estate Development

NAICS

Real Estate Property Managers (53131), Residential Property Managers (531311), Other Activities Related to Real Estate (531390)

SIC

Real Estate Agents & Managers (For Others) (6531), Real Estate (6500)

akta.pro primary industry

Multifamily Apartment Property Management (BPAJAFAA)

Keywords

• Luxury real estate development
• Condominium conversions
• Property management services
• Historic brownstone renovation
• Residential real estate investment

Headquarters

HQ city

Boston

HQ country

United States

HQ region

North America

Offices1 record

Markets served

GTM type

B2B and B2C

Offering type

Services

Cost components

Personnel, Supply Chain, Operations, Marketing or Sales, Infrastructure

Revenue model

1. Real Estate Development & Sales: Development and sale of luxury condominiums and single-family residences in Greater Boston. Revenue generated from property sales after development and renovation projects. The company has completed over 125 condominium conversions.
2. Property Management: Comprehensive property management services ensuring smooth operations, tenant satisfaction, and optimal returns on investments for residential and commercial properties.
3. Construction Services: In-house construction team led by Tom Helms handles gut renovations of historic brownstones and capital improvements at rental properties.

Pricing tiers

Go-to-market motion2 records

Distribution channels2 records

Marketing channels4 records

Core offering

Mainsail Management is a Boston-based real estate development and property management firm specializing in luxury residential properties in Greater Boston. The company develops, renovates, and sells luxury condominiums and single-family residences, while also providing ongoing property management, construction, and acquisition services to property owners and investors.

Product overview

Mainsail Management is a real estate development and property management company established in 1981, specializing in luxury residential properties in Greater Boston. The company operates as a unified offering combining property development, construction, investment acquisition, and property management services. Their product portfolio includes luxury condominiums (such as 142 Beacon Street, 117 Beacon Street, 94 Chestnut Street, 67 St. Botolph Street, 476 Beacon Street), new construction projects (99 Tremont Street with 62 units), multi-family residences (11 Melrose Street), and rental apartment communities (including 69 Bailey Street). Services offered include Property Management, Investments & Acquisitions, Development, and Construction.

Differentiator

Problem solved

Functional benefit

Products and services

• 142 Beacon Street A luxury property on the second block of Beacon Street in Back Bay, featuring three residences with 10,000 square feet across seven floors with river frontage and views of the Charles River Esplanade.
• 117 Beacon Street Two ultra-luxury 4-bedroom condominiums in Back Bay, converted from a single-family home, featuring a parlor duplex (3,047 SF) and a penthouse with private roof deck (5,035 SF).
• 170 West Brookline Street A luxuriously renovated single-family home in Boston's Historic South End, featuring four floors with modern and traditional finishes, custom kitchen, statuary marble master bath, residential elevator, and private roof deck.
• 94 Chestnut Street A two-family building in Beacon Hill's Flat of the Hill, featuring Unit 1 with 3 bedrooms and open concept living, and Unit 2 with 2 bedrooms custom-designed by IDF Studios.
• 476 Beacon Street Four grand residences in Back Bay converted from a 12-unit rental building, featuring a 3-bedroom duplex, 3.5-bath duplex with roof deck and Charles River views, and two 2-bedroom floor-through condominiums.
• 99 Tremont Street A new construction 62-unit condominium building in Brighton, developed in collaboration with Saracen Properties, featuring underground parking, gym, theater space, and outdoor living area.
• 69 Bailey Street 21 rental apartments in Dorchester, converted from a former VFW post, featuring studios, one- and two-bedroom units with leasing underway starting August 2024.
• 2A-4A Milford Street Four luxury condominiums in Boston's South End, each with 3 bedrooms, 2.5 bathrooms, and private outdoor space, completed in April 2025.
• Property Management Services Comprehensive property management services for residential and commercial properties in Greater Boston, ensuring smooth operations, tenant satisfaction, and optimal returns on investments. Includes dedicated property management with assigned property managers.
• Construction Services In-house construction team led by Tom Helms handles gut renovations of historic brownstones and capital improvements at rental properties, with skilled craftsmen managing all aspects of construction.
• Investments and Acquisitions Real estate investment and acquisition services in the Greater Boston market, with 20+ year investor partnerships delivering consistent positive returns. Supports identification, evaluation, and execution of investment opportunities.

Quantifiable outcome

• Over 125 condominium conversions completed in prime Boston areas
• +1 more outcomes

Named customers1 record

Segments2 records

Ideal customer profiles3 records

Technology focussed No

API detail

Has API

No

API docs

API detail

Core technology

AI maturity

App detail

Partnerships

Three partnerships are on record, tiered core and minor.

• Saracen PropertiescoreStrategic or Co-development PartnerCollaborative development partner on the 99 Tremont Street project in Brighton. This new construction condominium project includes 62 well-designed condominiums with amenities such as underground parking, gym, theater space, and outdoor living area. Joint venture combining Mainsail's development expertise with Saracen Properties.
• Grassi Design GroupminorStrategic or Co-development PartnerDesign collaboration on 170 West Brookline Street renovation in Boston's Historic South End. Grassi Design Group contributed to the blend of modern and traditional finishes across four floors, including high-end custom kitchen design.
• IDF StudiosminorStrategic or Co-development PartnerInterior design partnership for Unit 2 at 94 Chestnut Street. IDF Studios in San Francisco designed a custom 2 bedroom, 2.5 bathroom unit with second living room and custom details throughout.

Scale indicators5 records

Recent moves6 records

Expansion highlights4 records

Broad incumbents

• Lincoln Property Company: National residential and multifamily developer/manager — overlapping with Mainsail's property-management and development activities but at significantly larger scale and broader geography.
• Toll Brothers: National luxury homebuilder with significant presence in the Northeast — a larger, broader-incumbent player competing for high-end urban and suburban buyers in the same luxury price band that Mainsail's Boston product addresses.
• Equity Residential: Large publicly traded apartment REIT with Boston urban holdings — comparable to Mainsail's luxury urban rental and property-management activities at much larger scale and broader portfolio.
• Greystar Real Estate Partners: Largest U.S. multifamily property manager and developer — comparable to Mainsail's property-management arm at national scale, although not focused on Boston brownstone conversions.
• Berkshire Residential Investments: Institutional multifamily owner/operator with a Northeast urban footprint — comparable to Mainsail's apartment ownership and management operations but at a larger, more institutional scale.

Direct peers

• Samuels & Associates: Boston-based real estate developer active in Back Bay, Fenway, and other prime urban neighborhoods, building luxury and mixed-use product — directly comparable to Mainsail's luxury condo-conversion and ground-up development model in the same geography.
• Boston Realty Advisors: Boston-based real estate investment, development, and management firm active in urban residential — adjacent to Mainsail's combination of development, acquisitions, and property management.
• Triton Realty Group: Boston-area real estate investor and developer active in residential and mixed-use projects — overlapping with Mainsail's luxury residential development and property management activities.
• The Druker Company: Long-standing Boston real estate owner/operator with a portfolio of residential and mixed-use assets across the city — comparable to Mainsail as a Boston-based, multi-generational, owner-operator of luxury and residential real estate.
• The Hallmark Companies: Boston-focused developer and investor in luxury residential and mixed-use real estate — directly comparable to Mainsail's niche of in-city Boston luxury product and condo conversions.

Market position

Strengths5 records

Weaknesses5 records

Competitive moat4 records

Key risks5 records

Key highlights6 records

Customer concentration

• LinkedInlinkedin.com/company/mainsail-management-inc
• Instagraminstagram.com/mainsailmgmt

Revenue estimate

Valuation estimate

Number of profiles

Profiles6 records

Funding overview

Funding rounds

Investors

Funding detail is available on the Subscription and Enterprise plan.Contact sales →

M&A

Investments

M&A and investment is available on the Subscription and Enterprise plan.Contact sales →

Frequently asked questions about Mainsail Management