FILE - In a Thursday, June 18, 2015 file photo, Fitbit CEO James Park shows off one of his devices as he poses for photos outside the New York Stock Exchange, before his company's IPO. The company’s app... (Associated Press) 
 
 The company's app was the most downloaded on Apple's app store Christmas Day, a sign that many people couldn't wait to set up their Fitbit trackers after unwrapping them. It also suggests that Fitbit trackers were a hot seller during the holidays, despite increasing competition from Apple's smartwatch and other wearable devices. Investors were pleased, sending shares of the San Francisco company higher Monday. 
 
 The Fitbit app topped Apple's app store in the U.S. on Christmas Day and the day after, according App Annie, which tracks app downloads and rankings. That's far better than last year when the Fitbit app ranked at No. 18 on Christmas Day and No. 15 the day after, according to research from Raymond James & Associates. In a note to clients, Raymond James analyst Tavis McCourt called the numbers "impressive." 
 
 Fitbit declined to comment Monday. Apple did not respond to a request for comment. 
 
 While app downloads don't necessarily mean a tracker was sold, McCourt said it's a "good measure of relative sales success." 
 
 Retailers confirmed Monday that Fitbit trackers were in high demand during the holiday shopping season. 
 
 Macy's Inc. said the Fitbit's products sold "very well" at the department store. Discount retailer Target Corp. said the trackers were one of its top-selling electronics during the holiday season. And Amazon.com Inc. said the Fitbit Charge was one of its most popular items for customers that used its same-day delivery service in Chicago, Dallas, New York and other major cities. 
 
 App downloads could also lead to future sales. Users who track their health information on the app are more likely to buy another Fitbit device when they want to upgrade, said Ross Rubin, the senior director of industry analysis at App Annie. 
 
 Amanda Hetherington opened a Fitbit Flex on Christmas Eve, a gift from her son, and plans to buy more. 
 
 Hetherington, who says she is working on getting back into shape, downloaded the app on Christmas Day. Besides steps, she also plans to track what she eats and how much water she drinks with the app. 
 
 She's already making changes: This weekend she parked further away from a restaurant to get in more steps. 
 
 "I love it so much," said Hetherington, who lives near Columbia, South Carolina, "I'll probably get one for my husband for Valentine's Day." 
 
 Fitbit sells several different devices that track user's steps, calories or sleep patterns. They cost as little as $60 for a tracker that clips to clothing to about $250 for a watch. The company has already sold more than 13 million devices so far this year before the holiday shopping season, surpassing the 10.9 million total devices it sold last year. 
 
 But like a new gym membership, there is still the question of how long people will remain dedicated to their fitness trackers once the novelty wears off. Research firm Endeavour Partners estimated earlier this year that about a third of trackers get abandoned after six months. 
 
 On Monday, shares in Fitbit Inc. jumped 95 cents, or 3.3 percent, to $29.86. Still, they are down about 42 percent since reaching a high of $51.90 in August, a couple of months after the company's initial public offering in June. ||||| Wearable maker Fitbit was hit with a class-action lawsuit yesterday, just after the unveiling of its newest fitness watch. 
 
 In the suit, consumers from California, Colorado, and Wisconsin allege that the heart rate tracking in the Charge HR and the Surge, two products that came to market last year, is inaccurate by a "significant margin," especially during periods of intense exercise. The plaintiffs say that despite Fitbit's high-visibility advertising campaign around the heart rate tracking in its products, the monitors don't actually "count every beat." 
 
 One plaintiff said she bought a Charge HR because she wanted to track her heart rate accurately during exercise, but in her experience the heart rate monitors in the device didn't work properly. When she complained, Fitbit refused to refund her, she said. 
 
 It's not the first time Fitbit has faced a class-action suit. In the spring of 2014, consumers filed a suit alleging that the company misled them in the advertising of the Fitbit Force wristband after a number of wearers suffered skin rashes from the device. The Fitbit Force was eventually pulled from the market, and Fitbit later re-introduced a similar wristband called the Charge, which the company said had new materials that had undergone enhanced testing. 
 
 It's not the first class-action suit for Fitbit 
 
 The new lawsuit seeks injunctive relief as well as actual damages payments to compensate users for their "economic injuries" from Fitbit's heart-rate claims. 
 
 Fitbit said in a statement that it does not believe the case has merit and that it stands by its heart rate technology. It "strongly disagrees with the statements made in the complaint and plans to vigorously defend the lawsuit...PurePulse [Fitbit's proprietary heart rate tech] provides better overall heart rate tracking than cardio machines at the gym, as it tracks your heart rate continuously even while you’re not at the gym or working out. But it’s also important to note that Fitbit trackers are designed to provide meaningful data to our users to help them reach their health and fitness goals, and are not intended to be scientific or medical devices." 
 
 It's been a rocky week for Fitbit. Its newest watch, the Fitbit Blaze, was met with a lukewarm response after its unveiling yesterday, and Fitbit's stock dropped more than 18 percent, the lowest it has been since the company went public last summer. 
 
 This is partly due to the fact that many people see the new watch as directly competitive with Apple Watch. Like the Apple Watch, the Fitbit Blaze has a watch form factor, a color display, and the ability to track several different workout activities. However, Fitbit is not categorizing the Blaze as a "smartwatch" like the Apple Watch, because the Blaze doesn't support third-party apps, only Fitbit's own apps. Fitbit also works with different mobile operating systems, whereas Apple Watch works with iPhones. ||||| The stock market hated Fitbit's announcement of its new Blaze smartwatch at the Consumer Electronics Show yesterday, driving shares down nearly 20% to all-time lows. And it's not especially hard to see why. The Blaze, which you can buy starting in March for $199, is an ungainly competitor to the Apple Watch, which has become Fitbit's strongest competitor in wearable technology. To date, Cupertino's smartwatch hasn't much mattered to Fitbit which not only has outsold the Apple Watch by all accounts, but seemingly had a great Christmas too. Why then the stock slaughter? 
 
 In announcing its own smartwatch, Fitbit directly acknowledged that Apple is competition but it appears to have shown up to a Swiss Army knife fight with a spork . Fitbit CEO James Park seems to think his simpler device -- which is limited to fitness tracking, heart-rate monitoring, and a few other functions -- is just what the market ordered. Park told the Financial Times: "People have struggled with what the killer app is for smartwatches. For us it’s health and fitness. It’s really cumbersome on the Apple Watch sometimes to see what is my daily activity because they are trying to do so many things." 
 
 In two sentences, Park makes three pretty fundamental errors about the state of wearables today and how they are likely to progress. Let's break them down one at a time. 
 
 It's actually quite easy to check your activity on the Apple Watch 
 
 Having worn one since it came out last April, I can tell you I've become addicted to the fitness tracking functions on the Apple Watch. Accessing them could scarcely be easier. For every Watch owner, they are available in the home screen where all apps reside and through the Glance view which you reach by swiping up on the Watch face. Because it is so important to me, though, I made the Activity app omnipresent on my Watch face in the upper right hand corner. I can always see generally how I'm doing and a single tap on it brings up the detailed app view for me. 
 
 The killer app for smartwatches is notifications, not fitness tracking 
 
 While I do love Activity and completing the three rings each day -- a recent illness ended a 67-day streak for me of doing that -- the most fantastic part of the Watch experience has been allowing a limited set of short-form notifications to reach my wrist throughout the day. Texts from people I wish to hear from, e-mails from what Outlook calls the "Focused" inbox, calendar reminders and a very small handful of carefully selected alerts from other apps are my vibrations of choice. 
 
 For you, they might be eBay alerts, Venmo notifications, critical weather information or whatever you choose. On a Fitbit Blaze, you'll get texts, calls and calendar alerts and like it. There aren't apps, nor are any planned. The philosophy is consistent with what Park believed back in 2013 when the Fitbit Force was new and represented the company's tepid first steps into the smart-device world. Don't make it too complicated to encourage people to get up and move. Certainly a noble goal and certainly Fitbit's raison d'etre. 
 
 Fitness tracking is very likely a feature, not a product 
 
 With Fitbit riding its tracking devices to profits and market leadership, it's very easy to confuse its current position with one of having built a sustainable new market. That likely represents an incorrect analysis, however. More probable is that fitness tracking is today's MP3 player. Consider the lifecycle of that device: It was (1) initially revolutionary (2) rapidly cloned by dozens of companies (3) ultimately dominated by one company (4) eventually subsumed into a much more capable device. 
 
 Fitness tracking has already passed through the first two stages and is somewhere between stage 3 and 4. In the case of MP3 players, of course, the iPod was the dominant player and it was Apple that pushed music playing most aggressively into phones to largely kill off the music player. Unfortunately for Fitbit, while it surely does dominate the tracker market, Apple is again around and is using the Watch to try to make the tracker market much less relevant. 
 
 Which leads us to Park's third error: The Watch isn't trying to do too many things. On the contrary, today it only does a few things well enough. That's led to much consternation among technology writers that the Watch is somehow failing, despite more than 10 million sold already (and quite likely many more). 
 
 So what happens next? 
 
 Around the time the Blaze goes on sale, Apple will roll out the second generation of the Watch, which will likely be thinner, faster and more capable. It will also almost certainly remain $349 and $399, depending on which size the buyer chooses, making it much more expensive than the new Fitbit. That certainly leaves a market opening for the Blaze, though it becomes much smaller if Apple rips a page from its own prior playbook and keeps the original Apple Watch on sale at $249 and $299 -- a trick it's used with iPhone and iPad to great success. 
 
 The Blaze has some nice things going for it: The replacement bands are $30-130, less expensive than Apple's offerings especially if one wants stainless steel. Also the battery lasts 5 days vs. just 1 for Apple Watch. While that sounds appealing, it's a bit of a no man's land in battery life. Certainly a guarantee of a second day is nice in that you can forget to charge one night and you know you'll make it through the next day. But after that, the next real leap that really matters is a full week of battery life. Having owned a Fitbit that needed charging every 5 days or so I can report that never knowing when it would require being plugged in wasn't a convenience. It's almost easier to deal with the certainty of putting Apple Watch on its charger every night. 
 
 None of this means Fitbit is suddenly in trouble. For the time being, it has a near lock on tracking devices above the super low priced gear from Xiaomi -- which has no real presence in the U.S. so far -- and below Apple's Watch. But that position is precarious if it ultimately proves true that standalone trackers have little future or will be reduced to commodity items, like the throwaway MP3 players of the early 2000s. That leaves Fitbit needing to move upscale, where it started to go last year with the Surge line but increasingly competing with more capable products from Apple and perhaps a resurgent set of Android Wear devices like the incredibly sexy Samsung Gear S2. If that's the future, the Blaze isn't going to cut it either in capabilities or in the looks department. ||||| Yesterday Fitbit announced Blaze, a new "smart" fitness watch that tracks a bunch of different activities. And the immediate reaction to the watch was mixed. 
 
 Some of our Verge readers and Twitter followers said it looked way too big. Others saw it as an attempt to compete with Apple Watch. Investors didn't love it, either; the company's stock nosedived after the announcement. 
 
 We got some hands on time with the Blaze today at CES and got a closer look at some of its features. It's the first Fitbit to have a color LCD display, but it's also not a unibody watch. It consists of a pop-out tracker that you can pop into other bands and frames. It has optical heart rate sensors, but no built-in GPS. 
 
 It has "connected" GPS, which means you still have to carry your phone around for GPS 
 
 It's still not a very attractive watch. It is big, especially on my wrists. 
 
 But it's at least and lighter than the Fitbit Surge (one person at Fitbit's CES booth pointed out that it fit in the sleeve of his button-downs, unlike the Surge). It manages to cram a lot of features into a non-smartwatch smart watch, too. Until we get to test it for an extended period, we won't be able to really judge its capabilities — or its heart rate accuracy — but you can watch the video and decide for yourself whether its looks appeal to you. ||||| Fitbit is having a bad week. 
 
 On Tuesday, the maker of fitness trackers premiered a smartwatch, the Blaze. Shortly after, the company’s shares (“FIT”) tumbled, ending the day down 18%. 
 
 Now, Fitbit is facing a class action lawsuit alleging that its heart rate monitoring technology— which it calls PurePulse—is inaccurate, as first reported by The Verge. 
 
 Such technology is found in its Charge HR and Surge devices, as well as the newly announced Blaze. Essentially, Fitbit uses LED lights to monitor blood flow through a user’s wrist and, by using algorithms, can determine a user’s heart rate. Similar technology is used in the Apple Watch, along with several more competing smartwatches and fitness trackers. 
 
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 According to the suit, three different plaintiffs said they bought Fitbit devices based off the company’s advertised promise that it accurately tracked heart rates. Fitbit’s advertising materials often contain phrases such as “every beat counts” and “know your heart” in relation to the heart monitoring technology. 
 
 One participant in the suit had a trainer manually count her heart rate during a workout. Her trainer recorded a heart rate of 160 beats per minute (bpm) while her Fitbit Charge HR indicated her heart rate was only 82 beats per minute, according to the filing. Two other plaintiffs are mentioned in the suit, each citing similar experiences with a Fitbit PurePulse-equipped product. 
 
 WATCH: Why CES Still Matters 
 
 The suit goes on to say that a cardiologist, who used an electrocardiogram machine to compare results, found Fitbit’s heart rate sensor consistently reported inaccurate results. With a heart rate of 110 bpm or higher, the suit states the Fitbit devices often failed to record a heart rate at all. When a heart rate was captured, the reading was off by an average of 24.34 bpm, the suit said. 
 
 MORE: Fitbit Blaze is the Company’s Fitness-Focused Smartwatch 
 
 When contacted by Fortune, Fitbit provided the following comment: 
 
 ”We do not believe this case has merit. Fitbit stands behind our heart rate technology and strongly disagrees with the statements made in the complaint and plans to vigorously defend the lawsuit. Fitbit is committed to making the best clip and wrist-based activity trackers on the market. Our team has performed and continues to perform internal studies to validate our products’ performance. PurePulse provides better overall heart rate tracking than cardio machines at the gym, as it tracks your heart rate continuously – even while you’re not at the gym or working out. But it’s also important to note that Fitbit trackers are designed to provide meaningful data to our users to help them reach their health and fitness goals, and are not intended to be scientific or medical devices.” 
 
 Fitbit’s shares were down nearly 6% in mid-day trading at $22.86.
– Fitbit devices may have sold like hotcakes around the holidays, but the company is off to a miserable start in 2016. Just how bad has the past week been? Well, on Tuesday, Fitbit revealed Blaze, its new "smart" fitness watch. Immediately the company's stock fell 18%, reports Fortune. Some on social media say the watch is too big. Others say it's a knockoff of the Apple Watch, per the Verge, which admits it's "not a very attractive watch." Forbes jokes that Fitbit "appears to have shown up to a Swiss Army knife fight with a spork." Also on Tuesday, Fitbit was hit with a class-action lawsuit alleging that heart rate tracking in its Charge HR and Surge devices is way off. One plaintiff says a trainer counted her heart rate at 160 beats per minute, while her Charge HR read only 82 beats per minute. Fitbit says it "plans to vigorously defend the lawsuit," per the Verge. In the meantime, it's battling a third blow. On Wednesday, news broke that fraudsters had gained entry to Fitbit accounts using leaked email addresses and passwords from third-party sites. BuzzFeed reports at least 24 cases where fraudsters gained access to a user's GPS history, which includes past locations and sleep cycles, and attempted to defraud the company by requesting replacement items under warranties. Fitbit says only a "small proportion" of users were affected, but some tell BuzzFeed that Fitbit blamed them for using the same passwords across multiple sites. Fitbit says it's working on two-step verification for account changes but is "vigilant in identifying, blocking, and addressing this type of malicious nefarious activity."