India, Sept. 1 -- GoPro has suddenly become one of the most closely watched small-cap stocks on Wall Street after YouTube star Markiplier emerged as its largest individual shareholder, sending the struggling action-camera maker's stock sharply higher. But the dramatic rally has now been overtaken by an even bigger development: GoPro has agreed to merge with Starman Optical in a deal valued at $285 million.

The two developments came as GoPro tried to recover from a difficult year marked by falling sales, heavy losses, workforce reductions and concerns over its Nasdaq listing. The Markiplier investment briefly revived investor interest in the company, while the new Starman agreement could reshape GoPro's business beyond consumer cameras. ...