As a stock market investor and columnist, I have many successes – and many failures, too. One of my shortcomings is that I pay too little attention to impulse.

My instinct when a stock goes up 200% or more is to suspect it will fall back to earth. This is often wrong because the market leaders are often doing something right.

This year, Summit Therapeutics Inc. (SMMT) leads the gainers parade among large stocks (those with a market cap of $10 billion or more). It is up 628% through November 1st.

Caravan Co. (CVNA) is in second place with a gain of 333%. Next up is AppLovin Corp. (APP) by 310%, MicroStrategy Inc. (MSTR) by 264% and Vistra Corp. (VST) with a gain of 213%.

Here are some thoughts on these top-performing stocks.

Summit Therapeutics

Summit Therapeutics has jumped into the ranks of big stocks this year, raising hopes for its new cancer drug ivonescrimab. The company’s co-CEO, Mary Zanganeh, an immigrant from Iran, became a billionaire.

Its co-CEO, Bob Duggan, was already a billionaire by a decade, based on his previous drug development work.

Ivonescrimab is in phase 3 (end-stage) clinical trials in the US. It has already been approved for use in China. The company hopes it can be used to treat lung, kidney and breast cancer.

The drug was developed by Akeso, a Hong Kong company. Summit paid “$500 million for licensing and will pay up to $4.5 billion more if certain financial goals are met.

Summit has no revenue yet. Its market value as of November 1 is $14 billion.

Carvan

Retail investors are fascinated by Carvana, which sells used cars online and delivers them from buildings that resemble giant vending machines.

The Carvana stock delivers thrills and chills. In 2021, it reached an all-time high of $376. The following year, they dropped to less than $4. Now it’s back to about $229.

Short sellers like to bet against Carvana. As of mid-October, they had short-sold more than 13 million shares, or about 11 percent of all shares outstanding.

The numbers seem to support the short sellers’ view. Carvana’s debt is 10 times the company’s net worth. And the stock is selling for 102 times the company’s earnings – an inflated ratio in my book.

AppLovin

Based in Palo Alto, California, AppLovin provides software for mobile app developers. It listed Amanotes, CommerceBear, Kolibri Games, Music World Media, Ubisoft and Zynga among its clients.

This is a growing market, but growth has slowed a bit, according to EMarketer. The intelligence firm says the average smartphone user will install about 18.5 apps in 2023, down from about 21 in 2020.

AppLovin had about $2.35 per share in earnings over the past four quarters. Analysts are looking for steady growth to $5.86 per share in 2026. Out of 22 analysts following the company, 14 recommend it.

MicroStrategy

MicroStrategy, of Tysons Corner, Virginia, is a software maker. But the stock doesn’t move primarily on the results of that business. Rather, investors and speculators use it as a complement to Bitcoin.

MicroStrategy, of Tysons Corner, Virginia, is a software maker. But the stock doesn’t move primarily on the results of that business. Rather, investors and speculators use it as a complement to Bitcoin.

MicroStrategy, of Tysons Corner, Virginia, is a software maker. But the stock doesn’t move primarily on the results of that business. Rather, investors and speculators use it as a complement to Bitcoin.

The company is the largest corporate holder of Bitcoin, with a hoard of 252,220 bitcoins as of September 20 – about 1.2% of all coins outstanding. As of early November, Bitcoin stock is worth about $17.3 billion, or 37% of the company’s market value ($46.5 billion).

MicroStrategy has posted losses in three of the past four years and also in three of the past four quarters.

Vistra

Vistra Corp., based in Irving, Texas, is a power generation company with nuclear, coal, natural gas and solar facilities. Investors are excited about power generation now — for the first time in decades — because AI data centers use a lot of electricity.

The reasoning makes sense, and some smart investors are into the stock. I’m unlikely to join them as the company’s debt is three times its equity. I prefer stocks with less debt than equity.

Registration

I have been far too skeptical of big winners in the past. In 11 columns on this topic, the stocks I recommended gained an average of 16.9% over 12 months. That beats the Standard & Poor’s 500 total return index at 16.5%.

It would be nice if the story ended there, but it doesn’t. The big winners I told to avoid, usually because I thought they were too expensive, returned an average of 40.5%.

Please note that the results of my column are hypothetical and should not be confused with the results I obtain for clients. Also, past performance does not predict the future.

Disclosure: In a hedge fund I manage, I have a short position in MicroStrategy.