Justin Bajko

Starting as a One-Person Security Team

His career began on a one-person security team. On Expel's Nerdy 30 video series he summed it up this way: I’ve pretty much lived in managed security since the early 2000s. I started as a one-person security show in pharma research, moved into Symantec’s MSSP, and then joined Mandiant right as the industry was shifting toward more proactive detection and response.

Running Security Operations at Symantec, Mandiant, and FireEye

At Symantec he held a series of roles in the managed services business, from security operations center engineer to senior manager of the global threat response team, where he was responsible for detection capabilities, intelligence integration, and customer data ingestion for the company's managed security service customers.

He then became managing director of Mandiant's Managed Defense service, one of the first managed detection and response offerings. After that he was senior director of global service delivery for FireEye's managed service, FireEye as a Service, where he built and managed security operations centers around the world with a staff of more than 80 analysts. He summed up the Mandiant years by saying, Over time, I helped build what eventually became Mandiant’s MDR before co-founding Expel.

Co-founding Expel in Herndon, Virginia

Expel was founded in 2016 by Dave Merkel, Bajko, and Yanek Korff. The company monitors a customer's existing security tools around the clock, investigates the alerts they produce, and remediates confirmed threats.

Bajko's first title at Expel was vice president of strategy and business development. In Expel's account of his later promotion, the job was to stay close to customers and partners and make sure the company was heading in the right direction.

Expel's leadership page says Bajko comes from northeast Tennessee, follows the University of Tennessee football program closely, and spends his free time on cars, boats, travel, and video games.

Becoming Chief Strategy Officer in 2025

Expel announced on November 17, 2025 that Bajko had become chief strategy officer, responsible for setting and overseeing corporate and product strategy. In a short question-and-answer for the announcement, he described how buyers swing from one platform to specialist tools and back: There’s a larger trend around ‘platformization’ happening right now and whether it’s good or bad. This is a pendulum that has existed for some time.

He applied the same view to pricing and packaging. Customers don’t ever want to overbuy, but especially not in today’s economy. He also described how Expel's focus had moved from a pure analyst service toward what he calls a product-led service model, in which detection engineering and automation work alongside the analysts.

Views on AI SOCs and the MDR Market

Bajko is direct about the state of the market. Asked on the Nerdy 30 episode published November 13, 2025 to describe the MDR landscape in one word, he answered, If I had to choose one word? Gross. He explained that companies are unsure whether they are an MDR provider, an AI SOC, a co-managed SOC, a platform, or a hybrid, and that the labels have not settled.

In the announcement Q&A, he said that at his last count there were tons of AI SOC companies in the marketspace, and he argued that they are working on the old problem. To have a new market you need a new problem, and the problem being ‘solved’ by these solutions is the same as it’s always been. He wants a person in the loop: AI SOCs remind me of self-driving cars. They’re powerful, but you still need a human in the loop so it doesn’t run over the metaphorical cat. Asked whether AI SOCs solve something different from MDR, he said Honestly? No. and added that he expects the two approaches to converge.