Sports-first streaming TV service fuboTV (FUBO 2.46%) just announced some staggering second-quarter results. Revenue nearly tripled during the period, rising 196% year over year to $130.9 million. Zooming out even further, this is up from just $28.9 million in quarterly revenue only two years ago. 

Here's a closer look at the live streaming specialist's impressive second-quarter results and the key catalysts behind it.

fuboTV app displayed on a TV

fuboTV. Image source: fuboTV.

Strength all around

fuboTV truly fired on all cylinders during Q2. The company's subscribers -- the lifeblood of fuboTV's business -- more than doubled, growing 138% year over year and 15% sequentially to a record 681,721. Meanwhile, fuboTV's total subscription revenue grew 189% year over year to $114.4 million. Subscription upsells, improved subscription packaging, and greater advertising revenue per user were key drivers in the company's total top-line growth.

Engagement on the platform reached a record high. Users streamed more than 245 million hours during the period, up 148% year over year. Further, fuboTV's monthly active users streamed 134 hours per month on average during the quarter. This demonstrates "strong engagement with our platform's leading sports, news and entertainment content," management said in the company's second-quarter shareholder letter.

Surging advertising revenue

Of course, the biggest takeaway from the quarter was fuboTV's skyrocketing adverting revenue.

Ad revenue climbed 281% year over year, accounting for 13% of total revenue -- up from 10% of revenue in the year-ago period. Average advertising revenue per user rose 62% year over year and 22% sequentially.

"This growth demonstrates the foundational strength of our advertising model, offering brands the engagement and premium live content of linear TV, augmented by the efficiencies and first-party addressable targeting capabilities of a connected TV (CTV) platform," management said.

Improving profit margins

fuboTV has also been making significant progress toward becoming profitable. The company's adjusted contribution margin, or its average revenue per user less average cost per user, has increased from negative 4.4% in the second quarter of 2019 to 5.1% and 8.3% in the second quarters of 2020 and 2021, respectively. That's a 316 basis-point improvement over the last twelve months.

fuboTV's negative adjusted EBITDA (earnings before interest, taxes, depreciation, and amortization) margin has also seen dramatic improvement lately, going from negative 140% in the second quarter or 2019 to negative 36% in the second quarter of 2021.

"As we continue to lay the foundation for future growth," management explained about its aggressive investment strategy as the company attempts to capitalize on the immense growth opportunities in front of it, "our strategic investments in programming, team, technology and infrastructure have resulted in expected expense increases on an absolute dollar basis year-over-year." But management was sure to point out that "expenses continue to be significantly reduced in proportion to revenue."

The quarter continues to show a monster pureplay streaming-TV company in the making. Sure, costs remain high as the company continues to lose money. But considering how rapidly fuboTV is able to take its investments and turn them into revenue growth, investors should cheer this aggressive spending.