Utah Department of Transportation (UDOT) workers watch as a 2,178 ton bridge is moved by a Mammoet transporter onto support columns at the Diverging Diamond Interchange over Interstate 15 from the 'bridge farm' construction area 650 yards away in American Fork, Utah.

The U.S. municipal bond market grew slightly to $3.8337 trillion in the fourth quarter of 2016 from a revised $3.8334 trillion in the third quarter, according to a quarterly report from the Federal Reserve released on Thursday.

Households, or retail investors, held $1.644 trillion of muni bonds compared to $1.588 trillion the previous quarter.