What happened Aurinia Pharmaceuticals (NASDAQ: AUPH) stock has fallen sharply in response to a recent regulatory filing. Investors feeling queasy about the unlimited shelf registration statement that the company filed on Friday had pulled its share price down by 26.8% as of 10:49 a.m. ET Monday. So what In January, the Food and Drug Administration approved Aurinia's first drug, Lupkynis, for the treatment of lupus nephritis. As is often the case when an independent drugmaker launches its first drug, sales of Lupkynis haven't lived up to expectations. Image source: Getty Images. Sales perked up in the second quarter, but with revenues of just $14.6 million, Aurinia Pharmaceuticals isn't making ends meet. The company lost $50 million in the third quarter and $148 million through the first nine months of 2021. The stock was down on Monday because that new shelf registration statement suggests Aurinia Pharmaceuticals isn't very confident about Lupkynis' immediate future. The form filed states Aurina may issue an unlimited number of new shares, or securities that can convert into new shares, to fund operations. Unlike a typical secondary stock offering, shelf registration statements allow companies to issue new shares to take advantage of market conditions the moment they become advantageous. Now what Aurinia Pharmaceuticals finished September with $286 million in cash and marketable securities. If Lupkynis' sales trajectory continues along its present path, the company won't need to issue new shares that dilute its current shareholders. There is a dearth of effective lupus nephritis treatment options available, so it's probably too early to assume Aurinia Pharmaceuticals can't make money with Lupkynis. That said, it's probably best for investors to stay on the sidelines until we see Lupkynis sales truly lift off. 10 stocks we like better than Aurinia PharmaceuticalsWhen our award-winning analyst team has a stock tip, it can pay to listen. After all, the newsletter they have run for over a decade, Motley Fool Stock Advisor, has tripled the market.* They just revealed what they believe are the ten best stocks for investors to buy right now... and Aurinia Pharmaceuticals wasn't one of them! That's right -- they think these 10 stocks are even better buys. See the 10 stocks *Stock Advisor returns as of November 10, 2021 Cory Renauer has no position in any of the stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. The Motley Fool has a disclosure policy.Source