What's the most important ingredient for investing successfully? Time. However, some stocks require much less time to deliver huge returns than others.

You may have to be patient for significant returns if you invest in stocks that are about to announce major news or are entering a new growth phase. Here are two potentially explosive stocks to buy in April.

1. Viking Therapeutics

Viking Therapeutics (VKTX 0.56%) has already delivered explosive gains in 2024. The biotech stock is up nearly 330% year to date, but I think it has much more room to run.

The good news in February from a phase 2b study of experimental obesity drug VK2735 provided Viking's first big catalyst of the year. The company reported the injectable formulation of the drug helped patients achieve up to 13.1% placebo-adjusted mean weight loss after 13 weeks of treatment.

Only four weeks later, Viking announced more positive news. A tablet version of VK2735 achieved a placebo-adjusted mean weight loss of up to 3.3% after 28 days of treatment in a phase 1 study. The company plans to advance the oral formulation of the drug into a phase 2 clinical trial in the second half of 2024.

The obesity drug market could reach or even top $100 billion by 2030, according to some Wall Street analysts. Viking appears to be on the right track to claim a significant share of that market within the next few years.

In the meantime, the company could have another major catalyst coming soon. Viking expects to announce histology results from its phase 2b study evaluating VK2809 in treating nonalcoholic steatohepatitis (NASH) -- also known as metabolic dysfunction-associated steatohepatitis (MASH) -- in the first half of 2024. NASH/MASH is another massive potential market, with some analysts predicting over $100 billion in drug sales by 2030.

2. TransMedics Group

TransMedics Group (TMDX 4.18%) hasn't been as explosive as Viking. Its shares are down so far in 2024, but I predict this medical device stock will rebound strongly.

The company markets the Organ Care System (OCS), an innovative way to transport donor lungs, hearts, and kidneys. High percentages of donated organs don't make it to their intended recipients with the current standard of care -- cold storage. OCS addresses this problem and significantly reduces post-transplant complications.

Another major challenge for organ transplants was the unavailability of planes to transport organs. TransMedics tackled this problem head-on with its 2023 acquisition of charter-flight operator Summit Aviation. The company now has a fleet of airplanes dedicated to transporting organs.

Probably the main reason TransMedics stock isn't flying high right now is recent allegations made by Paul Gosar, who represents Arizona's ninth Congressional district in the U.S. House of Representatives. Gosar accused TransMedics of requiring hospitals to purchase a minimum number of OCS devices, prohibiting transplant centers from training their staffs on OCS, and using its National OCS Program (NOP) to reduce access as a way to boost profits.

TransMedics strongly disputed Gosar's allegations. The company made a good case for its position, in my opinion. I think this issue will likely prove to be much ado about nothing. I also expect significant growth when TransMedics reports its first-quarter results (probably in late May).