Starman Optical agrees to acquire GoPro in an all-cash deal valued at $285M, a premium of 29.5% to GPRO's last close; GoPro hit a market cap of $4B in 2014 (Prathik Jayaprakash/Reuters)

GoPro's stock price has soared after YouTube star Markiplier became the company's largest individual shareholder. The megastar YouTuber acquired an 8.5% stake in the struggling action camera maker over the weekend, causing shares to surge over 46% on Monday to close at 87 cents per share. Today, in premarket trading, GoPro's stock price has climbed another 93% to just over $1.69 per share, bringing the share price back to levels not seen since early January.

Markiplier, whose real name is Mark Fischbach, is one of the most popular YouTubers on the platform with over 38.9 million subscribers. He has transitioned from being a YouTuber to being a Hollywood auteur, producing the indie hit horror film Iron Lung, which grossed $51 million at the box office. Markiplier had previously used GoPro action cameras to capture behind-the-scenes footage for Iron Lung and was impressed by the company's new "cinema camera," the Mission 1 Pro ILS.

While Markiplier is now GoPro's largest individual shareholder, he does not hold a position with the company. However, his massive stake in the company has reinvigorated interest in GPRO shares among retail investors. GoPro's stock price has risen more than 100% in premarket trading this morning, after climbing 48% yesterday. The news of Markiplier's investment may have also given the company a lifeline on Nasdaq, which had given GoPro 180 days to get its stock price above the $1 minimum threshold for staying listed.

As of now, GPRO shares are well above the $1 listing threshold, potentially saving the company from delisting. However, it remains to be seen how long the Markiplier bump can last, as GoPro continues to face numerous challenges, including increased competition from other action camera makers and smartphone cameras, as well as a decline in camera unit sales.