In just the last six months, the S&P 500 has gained 10%, and while a rising tide usually lifts all boats, there are some companies that haven't done as well. In fact, it's as though they're holding on to the anchor and sinking fast.

Below, I'll take a look at why Fossil (NASDAQ:FOSL), Hertz (NYSE:HTZ), and J.C. Penney (NYSE:JCP) have not only seen their stocks decline, but have lost half their value or more. These stocks have sprung serious leaks suggesting there is something very wrong with their operations. So read on to find out what challenges are besetting these companies.

Woman selecting a Fossil watch

Image source: Fossil.

Fossil

Watchmaker Fossil is caught in the vortex of two forces that threaten to rip it apart: the decline of brick-and-mortar retail and the move away from traditional timepieces toward smartwatches. The centrifugal forces have sent Fossil's stock careening 58% lower in the last six months.

Shoppers aren't going to the mall anymore. As e-commerce continues to grow, and particularly as Amazon.com (NASDAQ: AMZN) provides one-stop shopping for virtually everything a consumer might need, a trip to the mall just isn't as necessary as it used to be. That's forcing retailers to shut hundreds of stores, and when one of these outlets closes, that's one less location where Fossil can sell its goods.

More concerning for the watchmaker is that it has completely missed the demand for smartwatches. You would think a company in this business would have seen the potential for the trend, but Fossil was very late in climbing on board. While it promised to make a big bet on technology and launched 100 wearables, that was more a desperate move than a carefully thought-out strategy. It has already lost substantial ground to Apple, Samsung, and Fitbit (even the latter was caught flat-footed by the preference for smartwatches as opposed to single-purpose fitness trackers). Now it's scrambling to catch up, which means any play Fossil makes is going to be simply a me-too item in a very crowded field.

Fossil's first-quarter results showed a 17% drop in sales in the Americas, generating a net loss of $1 a share, which was nearly four times worse than the $0.27-per-share loss Wall Street expected. Time does not appear to be on Fossil's side.

An empty shopping mall

Image source: Getty Images.

J.C. Penney

You can take the overview of retail troubles above and use it to explain what's causing J.C. Penney's woes. The department store chain was only just beginning to get its bearings after a near financial collapse a few years ago when retail's problems added instability.

Unlike the watchmaker, though, J.C. Penney's recent earnings results were slightly better than expected. While sales still fell year over year, and it posted a surprise adjusted profit of $0.06 per share, that was only the result of a one-time operating-asset sale. Customer traffic is down, and it looks like it will need to close hundreds of more stores to shore up its finances (that would hurt Fossil too, by the way, as it sells its watches in J.C. Penney's stores).

Management tried to remain upbeat about its prospects and said that while February was a lousy month for everyone in retail, J.C. Penney's March and April were much better in comparison. Investors weren't buying it, however, and caused its stock to drop nearly 25% in the days following the earnings report. The stock has lost its value since November.

Department stores like J.C. Penney and Macy's simply have too many stores. Because of the seismic shift in consumer shopping habits, the retailers need to dramatically shrink their footprint to be able to reflect decreasing demand, but the ripple effect such moves have only compounds the problems facing the chains.

Malls are turning into ghost towns once again, and investors in department stores like J.C. Penney should be scared for what that ultimately means.

Couple renting a car

Image source: Getty Images.

Hertz

In a way, the problems at car rental giant Hertz aren't all that different from those afflicting Fossil and J.C. Penney in that it, too, needs to deal with changing consumer preferences. Hertz's issues, though, don't stem from the way people shop, but rather from how they get around. With the proliferation of ride-hailing services like Uber and Lyft making it easy for travelers to get a ride when and where they need it -- and at significantly lower cost -- the need to actually rent a car has diminished.

Moreover, Hertz is also confronted with depressed used-car pricing. A large part of Hertz's business (which applies to any car rental company, for that matter) is selling the used cars that are retired from its fleet every year. The growth in car leasing from the automakers has created a glut of used cars on the market that is pushing prices lower, and the National Automobile Dealers Association says its used-car pricing index remains at its lowest point since 2010.

Compounding the problem are Hertz's own turnaround efforts, which include changing over its rental fleet faster. It has been dumping many of the compact and standard sedans in its fleet in favor of more popular SUVs.

The transition is a double-edged sword because it means Hertz's business is taking a big hit up front, but it just might bolster the business later as it would allow the company to charge higher rates for vehicles.

Still, Hertz needs to contend with customers opting for a lift with the ride-sharing apps. Hertz has tried to minimize the damage by partnering with both Uber and Lyft to allow people to rent a car and then drive for the services, but that only seems to delay the day of reckoning.

Hertz is in the midst of an industry upheaval, though not necessarily one the company shouldn't eventually be able to drive through.

Rich Duprey has no position in any stocks mentioned. The Motley Fool owns shares of and recommends Amazon, Apple, and Fitbit. The Motley Fool recommends Fossil Group, Inc. The Motley Fool has a disclosure policy.