Investors have been taken on quite the ride over the past 21 months. They've navigated their way through the quickest decline of at least 30% in the history of the benchmark S&P 500, and have reveled in what's become the strongest bounce back from a bear-market bottom on record.

But in spite of the S&P 500 hitting more than five dozen all-time closing highs in 2021, bargains still abound for opportunistic investors.

Even better, with most online brokerages doing away with minimum deposit requirements and trading commissions, any amount of money can be put to work and used to further your trek to financial independence -- even $100.

If you have $100 that's ready to be invested in the market, which won't be needed for bills or emergencies, the following three no-brainer stocks would make for perfect buys right now.

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Western Digital

Investors often think of growth stocks and value stocks as existing in their own realms. In other words, growth stocks usually trade at premium valuation multiples, whereas value stocks are typically slow-growing, mature businesses. But once in a while, we come across a company that fits the mold of both categories, and that's exactly what investors are going to get with storage solutions specialist Western Digital (NASDAQ:WDC).

Storage companies like Western Digital tend to be highly cyclical and prone to oversupply issues. Historically, when pricing power improves for hard-disk and solid-state drives, the key players tend to overproduce. This sends prices and profits lower and is what ultimately hamstrings the industry from maintaining premium price-to-earnings (P/E) multiples.

However, things really do look different this time. We've witnessed storage industry consolidation in recent years, and the coronavirus pandemic has seriously crimped global supply chains. Even if storage companies wanted to, they'd be unable to flood the market with product. This suggests that both pricing power and demand will remain high for the foreseeable future.

More specific to Western Digital, it should continue to benefit from a combination of shorter-term and long-run catalysts. In the coming quarter, the company should see a healthy boost in demand from gaming console manufacturers. New consoles tend to come out every five years. Though the newest consoles made their debut last year, the recession and supply chain issues have stymied sales. Since new consoles require more storage capacity, their rollout provides a steady (yet relatively short-term) boost for Western Digital.

What's far more exciting is how Western Digital is playing a key role in next-generation technology. It's a major player in data centers, which require beefed up storage options as businesses shift their data into the cloud. Further, the company's storage solutions are growing in demand for next-generation automobiles, which are increasingly becoming more and more high tech.

Western Digital looks like an absolute bargain at less than 8 times Wall Street's estimated earnings per share for fiscal 2023.

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Cresco Labs

For growth-oriented investors, the no-brainer stock you can add to your portfolio right now with $100 is U.S. multi-state operator (MSO) Cresco Labs (OTC:CRLBF).

For the past nine months, U.S. marijuana stocks have been in nothing short of a funk. The expectation with President Joe Biden entering the Oval Office in January was that federal legalization would be around the corner. However, pressing coronavirus issues have pushed federal cannabis reform efforts to the backburner.

What investors should realize is that legalization isn't necessary for U.S. pot stocks to thrive. As long as the Department of Justice maintains a hands-off policy and allows states to regulate their own weed industries, cannabis stocks can grow and be profitable. To date, 36 states have given marijuana the green light, in some capacity.

As for Cresco Labs, it has two strategies that should help it deliver the green for its shareholders. First, management hand tended to focus the company's retail expansion efforts on limited-license markets. These are states that limit how many dispensary licenses are issued in aggregate, and often times to a single business. States like Illinois and Ohio, where Cresco has a strong retail presence, are perfect examples. While this licensing cap might sound like a nuisance, it's actually beneficial for Cresco Labs. It's allowing the company to build up its brands and garner a loyal following without being overrun by a larger MSO.

The other key to success is Cresco Labs' industry-leading wholesale segment. Wall Street tends to be underwhelmed by wholesale revenue given its lower margin relative to retail. However, Cresco holds a highly lucrative cannabis distribution license in California, which is what allows it to place its proprietary products into more than 575 dispensaries throughout the state. In other words, Cresco is more than making up for low margins with exceptional volume.

With this two-pronged growth approach, Cresco Labs is well-positioned to make investors richer over time.

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Image source: Getty Images.

AT&T

A third and final no-brainer stock that investors can put $100 to work in right now is telecom giant AT&T (NYSE:T). For value and income investors, this one's for you!

AT&T has had a rough go of things over the past five years. The company's large debt load has been in focus, and its acquisition of DirecTV never quite paid the dividends that were expected. With more households than ever opting for streaming content instead of traditional cable or satellite TV, AT&T has been grasping for growth drivers. The good news is that two clear-cut catalysts have emerged.

In May, AT&T announced that it would spin off its WarnerMedia content division to merge with Discovery (NASDAQ:DISCA)(NASDAQ:DISCK). Combining forces will create a media giant with more original programming and intriguing sports content. Perhaps more important, the combination will result in more than $3 billion in cost synergies and allow AT&T's remaining operations to focus on debt reduction.

On a pro forma basis, these two companies have a little over 85 million subscribers. But according to Discovery CEO David Zaslav, who'll be taking over as the CEO of WarnerMedia-Discovery post-merger, reaching 400 million streaming subscribers isn't out of the question.

Aside from this transformative combination, the other major catalyst for AT&T and its shareholders is the ongoing rollout of 5G wireless infrastructure. It's been a decade since wireless download speeds were meaningfully improved, which means we should see a steady device replacement cycle take shape for years to come. Investing in 5G infrastructure upgrades won't be cheap for AT&T, but the bread-and-butter of the company's wireless margin derives from data consumption.

Even with AT&T expected to reduce its dividend following its WarnerMedia spinoff to a yield ranging between 4% and 5%, the company is simply too inexpensive to pass up. Opportunistic value investors can scoop up share of AT&T for less than 8 times forecasted earnings per share this year and just 9% above its book value.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.