Nobody likes to hear about their portfolio's value sliding in the wrong direction. That said, the world's best investors know that bear markets are the best times to be a net buyer of stocks. 

Fear of rising interest rates and the recession that they could cause has pushed the Nasdaq Composite index, which is chock-full of growth stocks, around 30.6% lower since the end of 2021. At times like these, investors terrified of what could happen in the short term are dumping their stocks and driving prices lower than they probably should be.

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Savvy long-term investors who understand that it's just a matter of time before the market recovers have been scooping up shares of these recently discounted growth stocks. Here's why.

Zoom Video Communications

Shares of Zoom Video Communications (ZM 3.29%) seemed unstoppable during the early days of the COVID-19 pandemic. Unfortunately, the stock has tumbled by more than half this year thanks to the unwinding of lockdowns and a general distaste for growth stocks caused by rising interest rates.

Zoom is growing quickly, but it isn't a long-shot tech business that's burning through cash reserves supplied by its investors. In fact, the company's operation is already profitable with earnings under under generally accepted accounting principles (GAAP) that came in at 4% of revenue during the company's fiscal second quarter ended July 31. 

Zoom launched a unified communications service called Zoom Phone in 2019 and it's rapidly gaining popularity with larger businesses. The number of customers with at least 10,000 paid seats more than doubled year over year in the fiscal second quarter. A pair of especially large clients pushed the total number of paid Phone seats past 4 million this August. With lots of room to grow and enterprise-level subscriptions providing relatively steady cash flows, this stock looks like a long-term investor's dream come true.

Shockwave Medical

Shockwave Medical (SWAV) is defying the trend with a price that has risen 55% this year. Shockwave manufactures the world's only intravascular lithotripsy (IVL) devices for the treatment of peripheral and coronary artery disease. The stock is way up during a difficult year for growth stocks because the company's devices are establishing a new standard of care for treating hardened arteries.

Shockwave Medical devices are essentially narrow catheters that slide into obstructed arteries and deliver powerful sonic pressure waves in order to break up calcified plaques. This stock is a great stock to buy now and hold for the long run because IVL is more than just a concept. IVL is clinically proven to be more predictable than the current standard method for treating hardened arteries.

In the absence of Shockwave's IVL devices surgeons rely on angioplasty, which involves little balloons that stretch an artery from the inside out in order to break up calcium deposits. In the Disrupt trial, patients with peripheral artery disease were 77% less likely to suffer from a split-open artery when treated with IVL versus angioplasty.

Duolingo

Shares of Duolingo (DUOL -0.91%) shot up during the early days of the pandemic along with demand for its language learning services. Unfortunately, bearishness for growth stocks across the board has knocked the stock down around 59% from its peak in 2021.

Duolingo boasts the top-grossing education application on Alphabet's Google Play Store and Apple's app store. At the end of the second quarter this year it had 3.3 million paid subscribers, which was 71% more than it had a year earlier.

Many of Duolingo's subscribers are native English speakers, but it's the much larger population of non-native English speakers that makes this stock a strong buy right now. The company markets an English proficiency test that is increasingly accepted by Western universities and employers. Second-quarter revenue from the Duolingo English Test soared 66% year over year to $8 million this year and a high rate of acceptance means it could continue to climb.

Duolingo's English proficiency test is already accepted by the 25 largest U.S. universities by enrollment size. Instead of viewing the app as a threat, educators regularly encourage students to use it to supplement their coursework. With institutions as eager to jump on board as individuals, the next chapters of this company's growth story could be the most exciting ones yet.