Once Upon a Farm (OFRM) stock surged 20% intraday amid heavy trading, after the company's Friday debut on the New York Stock Exchange, when the stock opened at $21 per share compared with its initial public offering price of $18.

More than 2 million shares of the company traded intraday.

Transocean (RIG) has agreed to acquire Valaris (VAL) in an all-stock deal valued at around $5.8 billion, the companies said Monday.

Shares of Valaris surged 35% as intraday trading volume soared to over 10.6 million from a daily average of roughly 1.03 million.

Nexstar Media Group's (NXST) proposed business combination with Tegna (TGNA) will "help knock out the Fake News" as competition increases, US President Donald Trump said in a Truth Social post over the weekend.

Shares of Nexstar jumped 9.5% as intraday trading volume climbed to over 720,900 compared with a daily average of about 307,000.

Price: 5.75, Change: +0.36, Percent Change: +6.66