Several years ago, Twitter seemed like it would be the social media darling of the decade. Founders had dreams of being the first Internet company to reach one billion users, making it "the pulse of the planet."

That's not going to happen, and investors are cluing in. Twitter had 328 million average monthly active users, or MAU, in the three months ending in June, which is unchanged from the previous quarter. The company's shares were down more than 10 percent this morning on the news.

The poor showing comes despite Twitter's role in the daily news cycle being more prominent than ever, since the platform often serves as President Donald Trump's favored medium of expression.

"If you really can't accelerate MAU interest given the daily tweets from POTUS, not sure when you will," Michael Nathanson, senior research analyst of MoffettNathanson Research, told Reuters.

Twitter experienced a net loss of $116.5 million in the second quarter, greater than the $107.2 million it lost in the same quarter last year. Perhaps worse, Twitter's quarterly revenue has started to drop for the first time in its history.

"Twitter is a 'growth' company that is shrinking," Bloomberg's Shira Ovide writes today . "It doesn't turn a profit under any conventional meaning of the word and it competes directly against Google and Facebook, two of the most successful companies of the last generation. Other than that, things in the Twitter-verse are peachy."

Last fall, there was talk that Twitter directors were interested in selling the company, but nothing has really come of those rumors yet. And the company's stock slide isn't a long-term trend—yet. Shares are up 4.5 percent since the beginning of the year and eight percent in the last 12 months.

The contrast with Facebook, which had shares reach a record high this morning, couldn't be sharper. Facebook has more than two billion users, and it had a 50 percent jump in mobile ad sales in the second quarter.

Facebook's shares rose six percent to $175 this morning, a gain worth twice the entire market capitalization of Twitter, notes Reuters.