DavidWeidner

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The financial media have celebrated, almost with fireworks, the twin events of Alibaba’s upcoming IPO and Apple’s product roll-outs.

SAN FRANCISCO (MarketWatch) — Beginning today, investors are presented with two “second-coming” opportunities. But the question whether to buy or sell has less to do with the unknown of how these opportunities perform initially, and more to do with something investors already know.

Let’s start with what’s happening.

Second, Alibaba Group Holding BABA, -0.09%  is set to offer shares to U.S. investors for the first time. The shares aren’t expected to hit the market until Sept. 18, but the Chinese online retailer and finance company priced its shares in the $60 to $66 range on Sept. 5, and its executives, along with a slew of investment bankers, launched a road show Monday. The story of this one is valuation. At what price point is Alibaba too expensive?

Alibaba takes $20 billion IPO sales pitch on the road

The potential and hazards of both big-hype initial public offerings and tech launches are well-known. And there have been terabytes of discussion and analysis of both events. There’s a lot of hype.

If you’re curious about Alibaba, you may want to read Jeff Reeves’ Sept. 5 commentary. “After that initial pop,” Reeves notes, “will come skepticism about valuation, high expectations.”

Philip van Doorn’s assessment of Apple stock. published Monday, makes the case that the product launches don’t have to be perfect — Apple is doing just fine without them. “Investors who are considering whether to own this stock for the long term, all the trends look good,” van Doorn wrote.

In writing about long-term investing, van Doorn hints at the single biggest critical piece of information an investor can have: time horizon. And though it’s not nearly this simple, there are generally two types of market participants: investors and traders.

Investors are more concerned with underlying assets (or if you’re of the Warren Buffett school, “intrinsic value”). They use research and have a long time horizon. This class is mostly populated by future and current retirees, pensioners and people saving for college or their first home.

Traders, however, work on the margins and trade as a part- or full-time job. Their sweet spot is the short-term move of an underlying security. They use momentum, sentiment and technical analysis, and their business is volume. They tend to borrow, manage or use other people’s money.

Neither of these is good or bad. Everyone has a role. Traders are essential for price discovery. They’re constantly gauging the marketplace for a security and helping to set a level that accurately reflects all of the moving parts — the economy, what rivals are doing, the latest jobs numbers — all of the short-term variables that impact the price of a stock.

In the same way, investors provide an underlying foundation. As long as they hold, there’s a floor.

This column rarely gives investment advice, and it’s not going to do so today. But if you’re considering a play on Alibaba or Apple, consider first what your objective is. If you want to take a short ride and make a quick gain and you’re playing with house money you can lose, by all means take your best shot and buy, sell or short.

But if you are looking for investments that will grow over time so you can send junior off to MIT so he can start an algorithmic flash-trading fund, don’t get too caught up in whether the new Apple iWatch will become the Zune of a new generation. And don’t worry if Alibaba soars to a total valuation that exceeds the planet Earth in the first day of trading.

Ultimately, these “second-coming” events (a phrase I heard about the Twitter Inc. TWTR, +1.73%  IPO hype from John Fitzgibbon of IPOScoop.com) usually create a stir at the time, but are soon forgotten. The reality is that Wall Street offers us a lot of second-coming deals.

No matter the time frame, it’s the cooler heads that find salvation.