At a time when the global stock market is suffering from uncertainty because of US tariffs, this could be a good time to buy some S&P/ASX 200 Index (ASX: XJO) stocks, according to one expert.

The fund manager L1 Capital has identified some businesses that look really cheap after weakness in their share prices.

Just because something has gone down doesn't mean it'll automatically go back up. However, the experts at L1 are confident these businesses have been oversold and could be excellent buys today.

Viva Energy Group Ltd (ASX: VEA)

Viva Energy says that it's a leading convenience retailer, a commercial services provider and an energy infrastructure business.

The ASX 200 stock operates close to 900 service stations across Australia and supplies fuels and lubricants to a total network of nearly 1,500 service stations. This business also operates the Geelong refinery in Victoria, plus it has bulk fuels, aviation, bitumen, marine, chemicals, polymers, and lubricants businesses.

L1 noted that the Viva Energy share price fell after releasing its 2024 result. While that was "broadly in line with guidance and market expectations", its FY25 first half guidance for the convenience and mobility business was "well below market expectations" because of slow ex-tobacco convenience sales growth, an ongoing "sharp decline" in tobacco sales and weak retail fuel margins to start the year.

The fund manager expects the FY25 second half to "improve significantly" for a few reasons.

It should benefit from acquiring the remaining interest in the Liberty Convenience business, the substantial synergies from combining the Coles Express and OTR businesses, its $50 million cost-out program and the potential for an improvement in fuel retail margins.

L1 said OTR remains a "proven, high-quality fuel and convenience retail offering".

The fund manager said:

There is significant earnings upside potential from rolling out OTR across the well-located, but historically under-invested Coles Express sites, within the initial set of conversions performing well.

Management have retained their $500 million EBITDA target for the convenience & mobility business (compared with $231 million EBITDA in 2024).

L1 also said the ASX 200 stock's commercial business is performing well and refining margins have improved from the trough in 2024.

The fund manager said that Viva trades at a "substantial discount to its global peers, despite the significant medium-term earnings upside potential in the business."

Mineral Resources Ltd (ASX: MIN)

Another under-pressure ASX 200 share that L1 pointed out was Mineral Resources.

This company is involved with iron ore mining, lithium mining and mining services.

Mineral Resources was another business that has suffered a large decline recently because of a delay to the ramp-up of the company's Onslow iron ore project and an additional $300 million capital expenditure to upgrade and repair the haul road connecting the project to the port after weather damage.

L1 has previously outlined why the investment team think Mineral Resources shares are undervalued.

The fund manager said it continues to believe that each of the ASX 200 stock's core segments "should see material improvement from current levels over the medium-term." L1 concluded:            

As a result, we think the risk-reward at the current share price of <$20 is extremely compelling, with significant upside potential as Mineral Resources executes its key growth projects.