While not naming the client, InnerWorkings revealed in a press release that a change in control at the large company resulting in the decision last month to redirect a significant portion of work to a provider with an existing business relationship with the client’s new management team.

InnerWorkings added it does expect to keep some of that client's work going forward.

"While we are disappointed by the revenue loss from a major client, we understand this risk presents itself when a client undergoes a change in control," president/CEO Eric Belcher added in a statement.

"We look forward to continuing to deliver excellent service and savings for them, albeit in a new reduced role"

Shares in the publicly traded company, which had been up 34% over the past 12 months, fell by as much as 25% in the day after the announcement.