South Mountain Merger Corp. , a special purpose acquisition corporation, or SPAC, said Monday it has reached a deal to merge with Billtrust, a cloud-based payment processing software company, in a deal with an enterprise value of about $1.3 billion. Upon closing, the company will change its name to BTRS Holdings Inc. and will trade on Nasdaq under a new ticker. The deal is expected to close in early 2021. Billtrust's management team will continue to lead the company, led by Founder and Chief Executive Flint Lane. "Customers use Billtrust's platform to transition from expensive paper invoicing and check acceptance to efficient electronic billing and payments, which accelerates revenue capture, generates cost savings, and provides a better user experience," the companies said in a joint statement. The new entity will be debt free and have $200 million in cash. SPACs, or blank-check companies, go public without having a business and then acquire one of more. The vehicle has become a popular route to public markets during the pandemic, raising record proceeds in the third quarter of $28 billion in 75 deals, a record that was more than triple the previous record quarter.