RAPID CITY, S.D. — Ketel Thorstenson, LLP, the largest accounting firm in the Black Hills, will merge with Casper-based Grooms & Harkins, P.C., in a strategic partnership set to take effect Jan. 1, 2026. The move expands KT’s service reach across South Dakota and Wyoming while strengthening both firms’ longstanding presence in the region.
KT CEO and Partner Nina Braun said the merger reflects a shared mission to advance high-quality accounting and advisory services throughout the Black Hills and Wyoming. “We’re bringing the best of both firms together,” Braun said. “Combining our strengths to offer broader services, deeper expertise, and greater value to our clients across South Dakota and Wyoming.”
Current stakeholders from Grooms & Harkins will become partners at KT, ensuring continuity for clients while adding new leadership depth to the firm.
Nic Grooms, managing shareholder at G&H, said the merger enhances available expertise for industries core to both states. “Our clients will benefit from KT’s comprehensive accounting and advisory services,” Grooms said. “Our shared expertise in the construction, agriculture, and nonprofit industries made this merger an ideal fit for our clients and staff.”
KT, which has established offices in Rapid City, Spearfish and Gillette, will now extend its footprint to Casper. The G&H office will adopt KT branding and transition to its systems as integration efforts continue into the new year.
Both firms emphasized their commitment to community involvement, workforce development and client-centered service — values deeply rooted in the Black Hills and central to the firm’s future direction.
Clients of G&H will continue to receive uninterrupted service while gaining access to expanded resources and advisory capabilities under the unified KT banner.
The merger becomes official Jan. 1, marking a significant step in KT’s growth strategy across the region and reinforcing Rapid City’s role as a professional-services hub in the Northern Plains.
