The Thrift Savings Plan has hit an eye-popping milestone. The Thrift Savings Fund balance — the total amount invested across the TSP's 4.5 million accounts — climbed to a record-high of $302.1 billion at the end of January, Tom Trabucco, the director of External Affairs at the Federal Retirement Thrift Investment Board, told In Depth with Francis Rose.

Trabucco called it a "big jump" from the end of December, when the TSP balance was $294.7 billion. The increase was bolstered by "outstanding returns" last month, he added. It's the first time the TSP has ever crossed the $300 billion mark, Trabucco said.

Trabucco said the TSP's size — it's the largest retirement plan in dollars and participants — helps to put the numbers in context. "Where the people are, the money's going to follow," he said. "As long as they're putting their money in — and they are."

In fact, participation numbers for January also increased, Trabucco said. The number of FERS contributors increased from about 2,020,000 to about 2,052,000, he said.

On the Roth TSP front, Trabucco said the Federal Register will publish draft regulations for the new plan Wednesday. "All of this is leading up to the rollout" in the next few months he added.