Raleigh-based Expion, a five-year-old social marketing firm with a high-profile list of clients and offices in the U.K. as well as China, has been acquired by San Francisco-based Sysomos.

Financial terms weren’t disclosed.

But look for Sysomos to be hiring more people in Raleigh where the Expion team will remain headquartered.

Expion clients include such giants as Coke, Subway, Mary Kay, Porsche and NBC Universal.

In an exclusive interview, Expion founder and CEO Peter Heffring, who launched the company in 2010, discusses the deal.

Why did you decide to sell the company?

Sysomos’ data expertise and technical infrastructure is a natural match for Expion, and the two companies’ strategic partnerships, impressive client rosters, and global offices are complimentary. This combined with the financial back of OMERS private equity to fuel our growth; this was right time and the right company.

Will you be staying with the combined company and if so in what position?

Yes, I will be President of Sysomos Platform division (effectively Expion for now).

Why did you decide to stay?

There is a great opportunity in the market right now for expansion globally. Leveraging the Sysomos infrastructure and the injection of significant new capital will allow rapid growth and value of the combined companies.

Is there a length of time contracted for your continuing service? No, I view this as great opportunity for me personally and love working with our outstanding Raleigh team.

Do you retain an ownership stake?

Yes, I am so bullish on our future that I have a retain a significant ownership stake.

Can you tell me the financial terms of the deal?

We are not disclosing deal terms.

What has been the secret sauce of your firm’s success?

It has been our dedicated focus and relentless drive to solve client marketer challenges combined with our strong customer service.

Will the combined company maintain a presence in the Triangle? Could it grow?

Yes, we are currently under rapid expansion across Sysomos and that will include hiring in the Triangle.

Were all your employees asked to stay with the new firm, or were there layoffs? Did some people choose to leave?

Everyone is offering a job and we expect the vast majority to stay.