Swift Transportation Co. and Knight Transportation Inc. will merge via a stock swap to form a new company, Knight-Swift Transportation Holdings Inc., Business Insider reported. The Phoenix-based companies announced Monday that their respective boards of directors unanimously approved the merger in an all-stock transaction that they said will create the industry's largest full truckload company. The two companies earned about $5.1 billion in total revenue and $416 million in adjusted operating income last year. The companies expect to achieve about $15 million in cost-saving synergies and pretax revenue in the second half of 2017, and up to $150 million in 2019.