With the stock market tapping fresh all-time records in recent sessions, price-to-earnings ratios are also increasing.

These ratios reflect whether a stock is potentially undervalued or overvalued, with a lower the price-to-earnings ratio (P/E) meaning the stock is a cheaper the buy. Savvy investors can find several companies with lower P/E ratios than their peers, which indicate they may be a bargain in their industry.

Below are four companies with significantly lower price-to-earnings ratios (P/E) than their peers. These ratios were calculated using the “trailing twelve months” method. With that calculation, the current price of the stock is divided by the earnings per share from the previous year.

Here are four companies in different industries that offer lower P/E ratios than their rivals. All figures are as of August 21, 2017.

1. Toll Brothers

In a housing market that is steadily recovering from its 2006 crash, stocks of developers and homebuilders have been on the rise. Among them, Toll Brothers Inc. (TOL) has one of the lowest price-to-earnings ratio compared to its peers.

Toll Brothers’ stock is up about 21 percent year to date, yet it still offers a lower-than-average P/E ratio of 14.0. The Pennsylvania-based company is the largest luxury homebuilder in the U.S. It recently reported that its contracts in the third quarter increased 24 percent from a year prior as millennial customers, or those under 35, accounted for 23 percent of its sales.

Toll Brothers rivals like NVR Inc. (NVR), Hovnanian Enterprises (HOV), and KB Home (KBH) have higher P/E ratios in comparison with 21.3, 19.0 and 17.0, respectively. (See also: What’s Driving the Boom in Homebuilding Stocks?)

2. General Motors Co.

Automakers are also seeing signs that their ailing sector may be improving, meaning General Motors (GM) could soon recover from sluggish sales.

New auto sales in the U.S. are expected to increase 1.3 percent in August from the year prior and rise 8.2 percent from July, according to Edmunds.   

"Any kind of sales lift after seven months of declines is encouraging … It's a small step in the right direction," Edmunds analyst Jessica Caldwell told The Street, noting that automakers still have “a long road ahead.” (See also: U.S. Car Sales Slide, Inventory is Up.)

Detroit-based General Motors (GM) has a price-to-earnings ratio of 5.63, well below its automaker competitors. Ford Motor Co. (F) P/E ratio is 11.3, Toyota Motor Corp.’s is 9.8 and Daimler AG (DDAIF) is 6.7. In the past year, GM’s stock has risen 11.6%. GM’s stock has had a volatile year, but is still up 2% year to date.

3. United Continental Holdings Inc.

Airline stocks have taken a dive after a rough earnings season, and analysts like JPMorgan’s Jamie Baker are advising investors to buy the dip.

"We believe the U.S. airline industry will continue to take steps to ensure profitability and continued balance sheet repair," JPMorgan analyst Jamie Baker said in a note to analysts, according to CNBC. (See also: The Industry Handbook: The Airline Industry.)

United Continental Holdings Inc. (UAL), with a price-to-earnings ratio of 7.9, is now among the bigger bargains in its industry after the stock fell about 15.6 percent since the start of the year. Shares were weighed in part on a pricing war with Spirit. In comparison, Delta Air Lines Inc. (DAL) has a P/E of 7.9, Southwest Airlines (LUV) has a 15.5 ratio and American Airlines Group Inc. (AAL) has 10.6.

United’s stock is up 30.6 percent in the past year.

4. Molson Coors Brewing Co.

Major players in the beer brewing industry have taken a hit with the rise of consumer interest in craft brewing. But for investors who expect these companies to find their footing, one brewer’s low stock prices is a stand-out bargain.

Molson Coors Brewing’s (TAP) price-to-earnings ratio of 9.0 is significantly lower than its brewer rivals, offering a substantial bargain.

In comparison, Anheuser Busch’s (BUD) P/E is 59.2, Boston Beer Co. (SAM) is 20.1 and Heineken’s (HINKY) is 20.1. (See also: Molson Coors Stock: Time to Buy After Decline?)