The Nasdaq Composite (NASDAQINDEX:^IXIC) had to deal with something on Tuesday that it hasn't encountered much in 2020: standing on the sidelines and watching other major market benchmarks hit new record highs. Yet the Nasdaq could only put up with that situation for a single day. Even as those other indexes took a break, the Nasdaq finished Wednesday up about 0.5% and reaching a new all-time record level of its own.

Plenty of stocks contributed to the Nasdaq's gains, including some of the biggest players in the stock market. Yet particularly notable among winners listed on the exchange were Moderna (NASDAQ:MRNA) and Appian (NASDAQ:APPN), both of which posted double-digit percentage gains that speak to their respective potential for long-term growth.

Moderna's vaccine is in demand

Shares of Moderna were higher by 11% on Wednesday. The biotech company is getting a bunch of orders for its mRNA-1273 coronavirus vaccine candidate, and today's move came in the wake of yet another big deal.

Four vials labeled COVID-19 vaccine.

Image source: Getty Images.

The European Commission agreed to buy 80 million doses of Moderna's vaccine, with an option to buy up to 160 million doses. The deal is contingent on mRNA-1273 getting approved by the European Medicines Agency, as well as on input from various member countries of the European Union.

The EU joins a host of other countries that have put in contingent orders for Moderna's coronavirus vaccine. The U.S. is among those expecting to get mRNA-1273 doses, along with Canada, the U.K., Japan, and several other countries across the globe.

It'll take time for Moderna to finish navigating the approval process and get its vaccine into use. But investors aren't waiting for that to happen, sending the biotech stock to its best level ever.

Could Appian be next?

Elsewhere, Appian saw its stock soar 32%. The company didn't make any announcements, and it wasn't immediately clear what was sending shares of the low-code software enabler higher. Yet it's reasonable to think that a deal elsewhere in the software space might have been what pushed Appian stock upward.

Reports surfaced that salesforce.com (NYSE:CRM) might be looking to acquire workplace collaboration software platform provider Slack Technologies (NYSE:WORK). The two companies are apparently in discussions regarding some type of collaboration or combination, although no final deal has been worked out at present.

Thus far, major acquisitions in the software-as-a-service space haven't been as plentiful as many might have expected. High valuations are part of the issue, although that can work to an acquirer's advantage if it uses its own stock as currency for purchases.

Appian's high growth rate, in-demand development platform, and reasonable $12 billion market capitalization put it in the sweet spot for would-be acquirers. Few speculated on who might be interested in picking up Appian, but the news of a possible Slack deal seemed to make investors consider the possibilities. For a company looking to add a successful SaaS stock business model to its existing business, Appian would be a solid choice.

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