Stocks have advanced since the start of the year, prompting the big question: Have we entered bull market territory? Though the S&P 500 has climbed more than 20% from its bear market low back in October, it hasn't yet reached new highs. That must happen before we call a bull market.

Meanwhile, some are saying the market has climbed too high too quickly -- led by only a narrow selection of stocks. And as a result, we may be heading for a crash.

But billionaire investor Ken Fisher doesn't buy this scenario. In fact, Fisher thinks the "doom and gloom" actually is a bullish sign, TipRanks reported. Let's check out the stocks Fisher is betting on -- and how you might win in this market, too.

From picking fruit to managing billions

First, a bit about Fisher. He's worth $6.6 billion now, but that wasn't always the case. As a teen, Fisher made $1.20 an hour picking fruit near his California home, according to a Forbes biography. He considered high school a "waste of time," so he dropped out and went to college for the "better classes."

Fisher went on to start Fisher Investments in the 1970s with $250. He's since grown that to more than $190 billion in assets under management. So it's clear that Fisher has a lot of valuable experience to share -- which makes him a great person to listen to now, in a complicated market.

Since the start of the year, technology companies have contributed the most to stock market gains. Some say this lack of breadth is a bad sign, and declines could be on the way.

But Fisher says the opposite. He calls this a "false fear," according to TipRanks. "And it screams that this megacap-led surge has legs -- maybe not this week or this month, but fully through 2023," Fisher said.

Fisher has big positions in life sciences company Danaher (DHR 0.32%) and oil companies Schlumberger (SLB -0.48%) and ConocoPhillips (COP 0.10%). And he expects these players to benefit from a market rally, TipRanks reported.

The three underperformed in the first half of the year. But these companies, with billion-dollar earnings over the past couple of years, offer bright long-term prospects. And new investors could pick up the shares for lower valuations compared to several months ago.

DHR PE Ratio Chart

DHR PE Ratio data by YCharts

How can you win?

Now, how can you win in today's market? You could follow Fisher and add these stocks to your portfolio -- and/or you could look for other buying opportunities, especially among large-cap stocks. The key is to invest in heavyweights that are reasonably priced right now and have the factors that will allow them to advance over time -- like leadership in a growth market and a solid earnings track record, for instance.

In some cases, these companies have been left out of the current market rally. And in other cases, they've gained but still have plenty of room to run. For example, you might consider a big pharma company like Pfizer (PFE 0.55%). The stock has dropped nearly 30% so far this year. That's left it trading considerably cheaper than certain rivals.

PFE PE Ratio Chart

PFE PE Ratio data by YCharts

Pfizer is expecting a drop in revenue this year as demand for its coronavirus vaccine falls. But the company is launching a record number of new products that could drive growth over time.

You also could take a look at Amazon (AMZN 3.43%). The e-commerce and cloud computing giant climbed more than 50% so far this year. But as Amazon benefits from growth in these industries over time, it could gain a lot more. And today, even considering recent gains, the stock still trades for only 2.4 times sales, lower than more than 4 a couple of years ago.

The most important thing right now is to keep buying strong players that can perform over the long term. If Fisher is right, you may see at least some of your investments climb in the coming months.

But even if they don't deliver right away, that's OK. If you've chosen solid companies with promising prospects, you might be setting yourself up for a big win over the long haul.