Shell Oil Co., the U.S. arm of Royal Dutch Shell Plc (NYSE: RDS.A), plans to move most of the operations at its company's downtown headquarters to new offices on the city's west side, Shell announced to employees on Sept. 20.

Only Shell Oil's U.S. trading floor with remain in Shell Plaza after the first quarter of 2017, the company said in a statement.

Shell follows ExxonMobil Corp. (NYSE: XOM), which relocated 10,000 employees from offices across Houston, including downtown, to a custom-built complex 25 miles north of the city in 2015.