Check out the companies making headlines after the bell Wednesday:

Shares of social media company Twitter (NYSE: TWTR) sank after the bell Wednesday after a quarterly earnings report revealed a decline in active users on the platform.

The company reported fourth-quarter earnings of 16 cents per share on $710 million in revenue. Analysts had expected Twitter to report earnings of about 12 cents per share on $710 million in revenue, according to a consensus estimate from Thomson Reuters.

Amazon (NASDAQ: AMZN) saw shares bounce after it announced a $5 billion share repurchase program . The buyback replaces a $2 billion buyback authorization from 2010 for the e-commerce company.

Networking equipment company Cisco Systems (NASDAQ: CSCO) saw shares tick up after the closing bell after it reported better-than-expected quarterly earnings and revenue. Cisco posted a 2 percent revenue increase and said it would add $15 billion to its share buyback program.

Shares of Tesla Motors (NASDAQ: TSLA) popped despite posting quarterly results far below Wall Street's expectations. The stock was helped by a positive 2016 outlook that predicted faster delivery growth .

The maker of premium electric vehicles reported a fourth-quarter loss of 87 cents, adjusted, per share on $1.75 billion in sales. Analysts expected Tesla Motors to post earnings of 10 cents per share on $1.79 billion in revenue, according to a consensus estimate from Thomson Reuters.

Digital game developer Zynga (NASDAQ: ZNGA) saw its stock dip after reporting a shrinking audience due to lack of new releases. The maker of games like "Words with Friends" and "Farmville" is transitioning toward more mobile traffic as the Web business continues to decline, founder Mark Pincus said, in a statement.

Expedia (NASDAQ: EXPE) shares moved higher in extended trade after the travel planning technology company reported year-over-year increases in bookings and revenue in the December quarter. Shares of competitors Priceline (NASDAQ: PCLN) and TripAdvisor (NASDAQ: TRIP) also rose after the news.

Shares of generic drugmaker Mylan (NASDAQ: MYL) dropped as it announced plans to acquire international specialty pharma company Meda. In addition to the merger, which is expected to produce synergies of $350 million, the company reported diluted earnings of $4.30 per share in the latest quarter.

And quarterly earnings boosted shares of phone, Internet and cable provider CenturyLink (NYSE: CTL), which slashed costs and added TV customers, even as high-speed Internet users declined.

— CNBC's Jacob Pramuk, Everett Rosenfeld and Krysia Lenzo contributed to this report.

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