ArcBest (NASDAQ: ARCB) on Tuesday after market close reported that its August tonnage increased 9% year-over-year, accelerating from July's 7.7% growth. The company also raised its third-quarter adjusted operating income guidance for its asset-light segment to $10 million-$12 million, up from the initial $6 million-$8 million forecast. This improved outlook reflects continued yield discipline and productivity improvements.