The old adage that "a rising tide lifts all boats" is wrong. Boats that have already submerged won't rise at all. Similarly, a rising stock market doesn't lift all stocks.

I'm not sure if there's an opposite to this saying. If there is, it's wrong too -- at least when applied to the stock market. A declining market doesn't pull all stocks down. As a case in point, here are three top biotech stocks that are defying the bear market.

1. Vertex Pharmaceuticals

Few stocks in any sector have outperformed Vertex Pharmaceuticals (VRTX 1.70%) in 2022. Shares of the big biotech are up more than 30% year to date. Vertex hasn't been in negative territory at all despite the overall market malaise.

One key reason why the stock has chalked up such huge gains is Vertex's underlying business performance. The company's revenue and earnings continue to grow robustly, thanks primarily to its powerhouse cystic fibrosis (CF) drug Trikafta/Kaftrio.

Investors also recognize that even better days could be at hand for Vertex. The company commands a monopoly in CF and has a clear path to expanding its market share. Vertex and partner CRISPR Therapeutics appear to be on track to win regulatory approvals for exa-cel in late 2023. The gene-editing therapy holds the potential to be a blockbuster one-and-done cure for rare blood disorders sickle cell disease and beta-thalassemia.

Vertex's pipeline features other promising late-stage programs as well. Inaxaplin targets APOL1-mediated kidney disease, which affects more patients than CF. VX-548 could be an effective and nonaddictive alternative to opioids in alleviating acute pain.

2. Neurocrine Biosciences

Neurocrine Biosciences (NBIX 2.08%) stands out as another biotech stock that's trouncing the market. Its shares have jumped more than 25% year to date. Since early May, Neurocrine stock has soared over 40%.

The company's tardive dyskinesia drug Ingrezza continues to enjoy strong momentum, with sales rising 30% year over year in the second quarter of 2022. Neurocrine even raised its full-year sales guidance for the drug to a range of $1.35 billion to $1.4 billion from its previous forecast of sales between $1.25 billion and $1.35 billion.

Everything hasn't gone Neurocrine's way this year, though. In August, the company reported disappointing results from a phase 2a clinical study evaluating NBI-827104 in treating the neurological disorder essential tremor. After the study failed to meet its endpoints, Neurocrine decided to throw in the towel on any further development of NBI-827104.

However, Neurocrine has plenty of catalysts on the way. It hopes to file for U.S. approval later this year for Ingrezza in treating a second indication -- chorea in Huntington's disease. Results from a late-stage study of the drug in treating schizophrenia are expected next year. The company also expects to report registration data in 2023 from clinical studies evaluating experimental drug crinecerfont in treating the genetic disorder congenital adrenal hyperplasia in adults and in children.

3. Alnylam Pharmaceuticals

Shares of Alnylam Pharmaceuticals (ALNY 5.21%) have risen nearly 15% so far in 2022. This performance is even more impressive considering that the biotech stock was down nearly 30% year to date in mid-May.

What turned things around for Alnylam? On Aug. 3, 2022, the company reported overwhelmingly positive results from a late-stage study of patisiran in treating transthyretin-mediated (ATTR) amyloidosis with cardiomyopathy, a rare, debilitating genetic disease.

Patisiran already won U.S. Food and Drug Administration (FDA) approval as a treatment for polyneuropathy in people with hereditary ATTR and is marketed under the brand name Onpattro. Alnylam now plans to file later this year for FDA approval of the drug in treating ATTR patients with cardiomyopathy.

That's not the only good news for the company. Alnylam won FDA approval of Amvuttra in July 2022 as a treatment for polyneuropathy in people with hereditary ATTR. It also announced positive results on Aug. 29 from a phase 2 study of experimental drug cemdisiran in treating immunoglobulin A nephropathy, an inflammatory disease that can lead to kidney failure. 

Best pick?

In my view, Vertex easily ranks as the best pick among these biotech stocks defying the bear market. The company is already highly profitable, with a large cash position. Vertex should have strong growth prospects with its CF franchise and its promising late-stage pipeline.

The bears are ruling on Wall Street in large part because of worries about inflation and the threat of a recession. I think Vertex is arguably the best stock to buy right now in the midst of this uncertainty.