NEW YORK — When Apple was an underdog, it had an easier time shrouding its product announcements in mystery and perhaps catching competitors off guard. But now tech companies are watching every one of Apple’s moves — and scrambling to get out in front of them.

Several are cramming product announcements into this holiday-shortened week. Nokia and Motorola Mobility, former leaders in the mobile race who are now also-rans, have scheduled events for Wednesday at which they are likely to unveil new smartphones. The next day, Amazon is expected to introduce new Kindle devices.

Sony and Samsung, among others, got a jump on things last week, unveiling new tablets and phones at a consumer electronics conference in Berlin.

But next week, the event calendar is largely blank — with the exception of an Apple news conference said to be scheduled for Sept. 12, at which the company will reveal its latest ­iPhone, said a person briefed on the plans who declined to be named.

“It seems that the rumor of an Apple announcement is having an effect on competitors’ announcements, unless it’s an amazing coincidence’’ that several events are scheduled this week and none the next, said Michael Gartenberg, a technology analyst at Gartner. “It does make you wonder if Apple has thrown the industry a little bit off balance and taken away a little bit of their confidence.’’

In past years, it was common for technology companies to deliver product news at trade shows. Now, some have scaled back their presence at those conventions and followed Apple’s lead in running their own elaborate news conferences, hoping to grab the news media’s undivided attention.

Fall product introductions are important to companies seeking to generate excitement ahead of the holidays. The fall has become jam-packed with news in recent years as both the number of companies and product lines have grown, with the addition of players like Amazon and its Kindle products and companies building mobile Android devices.

This year, Microsoft is releasing a new version of its Windows operating system. Windows 8 will bring with it an array of tablet computers powered by the software, including Microsoft’s own Surface tablet, due Oct. 26.

Later, Apple is expected to unveil a smaller iPad.