Shares of Moderna spiked as much as 8 percent after the biotech company announced that it is developing a 2-in-1 booster shot that would offer protection against both COVID and the seasonal flu, using the groundbreaking mRNA technology behind its coronavirus vaccine. The new jab, known as mRNA-1073, is “just the beginning of a new age of information-based medicines,” said Moderna CEO Stéphane Bancel. A combo vaccine that could treat multiple respiratory viruses at once is just one of the therapies based on mRNA technology that is showing promise. Pfizer’s partner on its COVID vaccine, BioNTech, reported this week that its mRNA cancer therapy is showing itself to be effective at blocking certain types of tumors in mice. The company is now recruiting for human trials for that vaccine. Pfizer and BioNTech also plan to seek approval for their COVID vaccine in young children in the coming weeks.

El Salvador this week officially adopted Bitcoin as legal tender, the first country to do so and a landmark moment for the legitimization of cryptocurrencies. The rollout was rocky, with the government briefly shutting down its official wallet app because of technical glitches. The price of Bitcoin sank 18 percent that same day and has been treading water around $46,000 ever since. Meanwhile, Coinbase has caught the attention of federal regulators. CEO Brian Armstrong revealed to investors that the SEC has notified the company that it may sue over a lending product that Coinbase plans to launch in the coming weeks. Armstrong said he’s been trying to engage with the government since before Coinbase became the first crypto exchange to go public, but officials have refused to meet with him. Shares of Coinbase fell 10 percent on the week. 

GameStop shares pared much of the losses from a significant post-earnings sell-off, coming back to close fractionally higher on Thursday after being down as much as 11 percent during the same session. The video-game retailer that’s been a darling of retail traders this year did not provide much in the way of an update on its high-profile e-commerce strategy, nor did the company give forward guidance. The last quarter’s results came in mixed, with sales improving and its debt load almost gone, but the company still reported a wider-than-expected loss. GameStop shares are up more than 1,000 percent year-to-date. 

Speaking of meme stocks, AMC Entertainment got a strong push on the back of a shockingly strong Labor Day weekend at the box office. Marvel’s Shang-Chi and the Legend of the Ten Rings brought in $90 million over the holiday, easily breaking records for what is typically a sleepy weekend at theaters. But more importantly, Shang-Chi’s strong opening weekend -- unlike some other Disney flicks, it wasn’t released “day-and-date” -- appeared to show that moviegoers are increasingly ready to go back to the cinema. To that end, AMC announced it is launching a $25 million ad campaign -- the first time the theater chain has ever advertised on TV -- intended to remind viewers why they liked going to the movies pre-pandemic. Shares of AMC were up more than 10 percent on the week.

Lululemon continues to be one the retail sector’s biggest winners coming out of the pandemic. Lulu shares hit a new all-time high after a blowout earnings report. The athleisure juggernaut beat on the top and bottom lines and said it was on track to reach its 2023 revenue target two years ahead of schedule. Sales are up double-digits domestically, overseas and in both the women’s and men’s lines, and CEO Calvin McDonald said the quarter would have been even stronger if not for the supply-chain disruptions that continue to hamper many retailers. Lululemon is facing some new competition coming down the pike after one-time partner Peloton announced its first private label apparel line based on feedback from its members. Shares of Lululemon and Peloton were up 9 and 15 percent this week, respectively.