The market's been rallying since start of last year. The S&P 500 has soared 24% in that time, but there are many stocks that have performed even better.

Square (NYSE:SQ), Shopify (NYSE:SHOP), and Weight Watchers (NASDAQ:WW) have more than tripled since the beginning of 2017. The stocks have delivered life-altering wealth over the past 14 months. Let's explore how they have rocked the market and what the future may hold for investors. 

Hands holding a blue credit card and swiping it on a Square register with a chip card reader.

Image source: Square.

1. Square -- Up 242%

We're evolving into a cashless society, and Square is helping small merchants and enterprising individuals swipe credit cards to complete transactions. Its platform helped settle up a record $17.4 billion in gross payment volume during the third quarter of last year, and the tally should be markedly higher when it reports its results for the seasonally potent fourth quarter after today's market close. 

Square's been raising its guidance higher with every passing quarter, and it was targeting roughly 40% in adjusted revenue growth for all of 2017 last time out. It has also generated recent interest from speculators after it became an early adopter of bitcoin marketplaces. However, Square itself was already booming as a payment platform before the bitcoin sizzle.  

Analysts see Square moving higher. Josh Beck at KeyBanc boosted his price target from $40 to $52 last week, expecting a strong beat in this week's report. Last month, it was Dan Dolev at Nomura Instinet getting even more aggressive, boosting his price goal from $48 to $64. 

2. Shopify -- Up 223%

Shopify is helping get small merchants with online aspirations up and going on the internet. There are more than 600,000 merchants relying on its intuitive platform to seamlessly create e-commerce potential. 

The company is growing at a heady clip. Revenue rose 71% in the fourth quarter, as a 67% uptick in subscription revenue and a 74% burst in merchant solutions revenue combined for another blowout quarter. Shopify's adjusted profit of $0.15 a share was three times what analysts were forecasting, but the bottom-line beat shouldn't come as a surprise since Shopify has beaten Wall Street profit targets by at least 60% in each of the past four quarters. 

At least six analysts have jacked up their price targets following the strong quarter. There will always be concerns that someone will come up with a better e-commerce platform or that the addressable market will be limited, but until Shopify shows signs of mortality, it will continue to be a market darling. 

3. Weight Watchers -- Up 526%

One of the market's biggest winners has done more than merely triple. Shares of Weight Watchers have popped more than sixfold. The provider of weight management support and solutions initially got a boost when Oprah Winfrey became a stakeholder and spokesperson in 2016, but the stock really started moving in 2017 when it began to post growth in its subscriptions. 

Weight Watchers has posted seven consecutive quarters of year-over-year revenue growth, and we'll see if it can stretch that streak to eight periods when it joins Square in announcing financial results after today's market close. Winfrey has made Weight Watchers relevant again, something that seemed like a daunting task in an era of dieting apps and free online support groups.  

Earlier this month, Weight Watchers impressed the market by putting out aggressive long-term goals. It laid out its strategic vision that targets $2 billion in revenue by 2020, well ahead of the $1.16 billion it generated in 2016. 

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.