The order includes an option for 12 more LR2 vessels that may be exercised over the next 18 months, with each costing $47m.
Under the deal, STX has agreed to defer the majority of the purchase price of the vessels until delivery; Teekay expects to finance the payment instalments with its existing liquidity, which was $327m as of the end of 2012.
Teekay Tankers chief executive officer Bruce Chan said that compared to the current LR2 fleet, the fuel-efficient design of the new vessels is expected to help achieve fuel savings of about 20-30%.
"Furthermore, we believe the vessel deliveries are well-timed to benefit from expected improvements in refined product and global crude oil tanker market fundamentals," Chan said.
"The shift in global refining capacity east of the Suez Canal, development of new long-haul product tanker trading patterns, including the potential for increased US exports, and a relatively modest orderbook, make the LR2 segment a particularly attractive growth area for Teekay Tankers," Chan added.
Teekay expects to secure long-term debt financing for the four vessels before their delivery, which is scheduled to take place between late 2015 and early 2016.
Following delivery, the new vessels will be operated in Teekay’s Taurus Tankers LR2 Pool, which the company says is one of the world’s largest LR2 pools with about 20 tankers.
Teekay owns a fleet of 27 double-hull vessels, including 11 Aframax tankers, ten Suezmax tankers, three LR2 product tankers, three MR product tankers and has time-chartered two Aframax tankers.