Among the companies with shares expected to actively trade in Wednesday's session are Alcoa Inc. (AA), Yum Brands Inc. (YUM) and Knight Transportation Inc. (KNX).

Alcoa swung to a third-quarter profit, as the aluminum maker reported lower costs that bolstered the bottom line, though revenue fell slightly due to weaker shipments. Results easily topped analyst expectations, sending shares up 3% to $8.18 in after-hours trading.

Yum's third-quarter profit fell 68%, as the parent company of KFC, Taco Bell and Pizza Hut continued to take a hit from its Chinese operations. Shares were down 7% to $66.65 after hours, as the company lowered its expectations for its Chinese division, and its results came in below Wall Street expectations.

Knight Transportation cut its third- and fourth-quarter earnings guidance, as a variety of factors hurt the truckload carrier's results, including weak freight demand and lower miles per tractor. Shares dropped 5.8% to $15.50 after hours.

K12 Inc. (LRN) on Tuesday said its average student enrollments for the fiscal first quarter came in below the company's expectations. Shares were off 18% to $23.50 in after-hours trading, as the online-education company also offered revenue guidance for the fiscal year below Wall Street estimates.

Shares of Lpath Inc. (LPTN) slid in after-hours trading Tuesday, after the biotechnology company warned Pfizer Inc. (PFE) may divest itself of its exclusive option to co-develop the smaller firm's leading product candidate. Lpath's stock fell 9.8% to $4.40 in after-hours trading.

 
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Metals distributor A.M. Castle & Co. (CAS) issued preliminary third-quarter results that fell short of analyst expectations due to soft selling prices and challenging industry conditions.

Private-equity firm Apollo Global Management LLC (APO) is trying to sell the professional business of McGraw-Hill Education, which it bought earlier this year from the company now known as McGraw Hill Financial Inc. (MHFI), according to people familiar with the matter.

Callidus Software Inc. (CALD), a provider of sales and marketing software, raised its 2013 revenue outlook on expectations the company's third-quarter revenue will come in stronger than previously expected.

Biopharmaceutical development firm CytRx Corp. (CYTR) and early-stage diagnostics company Cancer Genetics Inc. (CGIX) separately disclosed plans to sell common stock. CytRx is aiming to raise money to fund its clinical trials, while Cancer Genetics wants to hire more sales and marketing personnel, as well as fund research and development.

Jos. A. Bank Clothiers Inc. (JOSB) has approached Men's Wearhouse Inc. (MW) about a combination that would create a nationwide powerhouse in men's apparel, according to people familiar with the matter. It isn't clear whether the approach, made recently, will lead to a deal, or what form any such tie-up would take, The Wall Street Journal reported.

Mistras Group Inc.'s (MG) fiscal first-quarter earnings rose 32% on revenue growth and a boost from a favorable acquisition-related adjustment.

Write to John Kell at john.kell@wsj.com

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