Check out the companies making headlines after the bell:

Sonic Automotive stock plummeted nearly 10 percent in after-hours trading. The automotive retailer said that gross margin pressure in key brands negatively impacted its second-quarter results. Jeff Dyke, Sonic Automotive's executive vice president of operations, said its BMW and Honda dealerships faced lower gross profit per unit due to "lower manufacturer-to- dealer incentives on certain models."

Shares of CSX were up nearly 3 percent in after-hours trading. The rail transportation company beat analysts' estimates on earnings for its second quarter, posting $1.01 per share versus the 87 cents per share that was expected. CSX also beat analysts' revenue expectations, generating $3.1 billion versus the $3 billion expected.

United Continental stock was up more than 3 percent in after-hours trading. The airline beat analysts' expectations, earning $3.23 per share versus the $3.07 that was estimated for its second financial quarter. United also beat analysts' expectations on revenue, generating $10.78 billion versus the $10.72 billion that was expected.

Shares of Texas Instruments were down nearly 2 percent in extended-hours trading. The semiconductor company's president and CEO Brian Crutcher resigned amidst violations of the company's code of conduct. Chairman Rick Templeton will re-assume the roles of president and CEO.



