Usamp, a US-based online market research company, has closed a series D round of financing for $15m from venture capital firm OpenView Venture Partners and investment manager DuPont Capital Management, which invests on behalf of US-based chemical company DuPont’s pension fund.

Usamp has now raised a total of $29.5m, including a series C round of $10.3m in which OpenView Venture Partners participated, a series B round of $3m in 2009, and a series A round of $1.29m in 2008.

Alan…