Check out which companies are making headlines after the bell Monday:
Allergan - Sources told CNBC activist investor William Ackman and Valeant Pharmaceuticals were teaming up to pursue a takeover of the specialty health care company. Shares of Allergan and Valeant rallied in after-hours trade.
Facebook - Credit Suisse upgraded the social networking site to outperform from neutral. Shares gained in after-hours trade.
Netflix - The online provider of subscription entertainment reported first-quarter earnings per share of 86 cents on $1.27 billion in revenue, versus expectations of EPS of 83 cents on $1.266 billion in sales. Its shares rose in after-hours trade.
Rent-A-Center - The provider of rent-to-own durable goods posted first-quarter earnings per share of 57 cents on $833.7 million in revenue, versus estimates of EPS of 54 cents on $839 million in sales. Its shares climbed in after-hours trade.
Waste Connections - The provider of municipal sold waste services posted first-quarter earnings per share of 44 cents, excluding items, on $481.7 million in revenue, compared to expectations of EPS of 41 cents on $475 million in sales.
Zions Bancorp - The regional bank reported first-quarter earnings per share of 41 cents on $554.8 million in revenue. Analysts polled by Thomson Reuters had expected earnings of 42 cents a share on $543.7 million in sales. Its shares were little changed in after-hours trade.
—By CNBC's Kate Gibson.
Questions? Comments? Email us at marketinsider@cnbc.com