Check out the companies making headlines after the bell Monday:
McDermott International stock whipsawed after the bell, jumping more than 5.5 percent before declining more than 1.5 percent. The oil and gas company announced a $6 billion merger with Chicago Bridge & Iron Company. The deal will grant McDermott shareholders will have majority stake in the new company, which will be based in Houston.
Shares of Chicago Bridge & Iron stocks also jumped about 5.5 percent falling back a little to rise half a percent.
Roku stock climbed more than 1 percent in extended trading. Morgan Stanley reported a 5.1 percent passive stake in the the streaming device company.
Shares of Kratos Defense and Security Solutions rose nearly 2 percent in the extended session. The information technology defense company announced Monday it received a $27 million unmanned drone contract from the U.S. government.
Heico stock rose nearly 2 percent on the extended session, on relatively light volume. The aerospace and electronics company reported fourth quarter and full year financial results that demonstrated growth since the 2017 acquisitions of AeroAntenna Technology and Interface Displays & Controls.