It's been a rough year for The Trade Desk, and Monday's after-hours session didn't help. The ad-tech company's shares took a dip after it filed paperwork with the SEC for a mixed shelf offering.

For those not fluent in SEC-speak, a shelf offering is like a financial rain check. The Trade Desk can now, at its leisure, offer and sell common stock, preferred stock, debt securities, warrants, or units. It's a flexible setup that lets the company tap the markets when it wants, without having to re-file every time.

The catch? We don't know the size or terms yet. The company will need to file a prospectus supplement each time it actually decides to sell something. So this filing is more of a "we might" than a "we are."

As of June 30, The Trade Desk had about $1.12 billion in cash and cash equivalents on hand. So it's not exactly desperate for funds, but the filing gives it options.

Investors, however, didn't love the news. TTD shares were down 2.13% in after-hours trading, sitting at $12.99 at publication time. That's a far cry from where the stock started the year, down roughly 65% year-to-date. It's also hovering near its 52-week low of $12.83, hit in early August.

So what's ahead for TTD? The shelf offering adds a layer of uncertainty, but with a solid cash position, the company has some breathing room. Investors will be watching closely to see if the company actually uses this filing, and if so, for what.