Here’s a look at some companies that were making waves in after-hours trading: Discover Financial Services — Shares rose 2.7% after Discover Financial Services reported second-quarter results. The banking and payments company reported net interest income of $3.52 billion, beating the FactSet consensus estimate of $3.46 billion. Earnings per share of $6.06 beat analysts’ estimates of $3.10. Kinder Morgan — Shares fell 2.8% after Kinder Morgan reported weaker-than-expected quarterly results. The pipeline operator’s second-quarter adjusted earnings of 25 cents per share fell short of the 26 cents per share expected by analysts surveyed by FactSet. Revenue also missed expectations. United Airlines — Shares edged down 0.3% after United Airlines reported mixed second-quarter results. However, revenue of $14.99 billion fell short of expectations of $15.06 billion. Steel Dynamics — Shares of the steel maker rose nearly 2%. Steel Dynamics reported second-quarter revenue of $4.63 billion, or $2.72 a share. Analysts surveyed by LSEG expected earnings of $2.67 a share and revenue of $4.43 billion. Alcoa — Shares of the aluminum maker rose 1.5%. Alcoa posted adjusted earnings of 16 cents a share, beating analysts’ estimates of 9 cents a share, according to LSEG. Revenue also beat expectations, coming in at $2.91 billion, while analysts had expected $2.84 billion. — CNBC’s Darla Mercado contributed to the report.