SO FAR AOL's shareholders don't seem thrilled about swallowing Time Warner: Since Monday, when the two companies proposed what would be the world's biggest ever merger, AOL's shares have tumbled. But the questions for consumers, if the deal is consummated, go beyond the stock price. Might the merger dull the diversity of the media? Might it drive up the price of Internet access?

The quick answer to these questions is: Relax. This is an apples-and-oranges merger: AOL and Time Warner occupy different bits of the media-Internet world, and joining the two companies together does not create new concentrations of power in any particular market. For example, AOL has half the market for the dial-up services that link computers to the Internet; but the merger would barely enlarge its roster of 20 million customers, since Time Warner's Road Runner dial-up service has only 300,000 subscribers. Time Warner already is the world's biggest movies-music-magazines conglomerate; merging with AOL's Internet business would not increase its share of that market.

If there is a worry, it is more subtle. The merger may not directly increase AOL's share of dial-up customers, nor Time Warner's media clout, but it could do so indirectly, if, for example, AOL's Internet customers were steered to Time Warner's online magazines and other products. Equally, AOL's privileged access to Time Warner's infotainment might help the firm to attract yet more dial-up customers, diminishing competition.

The chieftains of AOL and Time Warner protest that exclusive ties between Internet portal and media content are not in their interests. If AOL tried to deprive its Internet customers of non-Time Warner products, those customers will switch to other Internet service providers; if Time Warner stopped distributing its wares through non-AOL outlets, it would be shooting itself in the foot. Therefore, commercial calculation can be relied upon to drive the merged company to "open strategies," minimizing the competitive threat to rivals.

It's true that if AOL crudely excluded non-Time Warner products, it would indeed lose customers. But a bias in favor of content created by Time Warner is likely, and that might harm rivals. The question for consumers and regulators is how severe that harm is. For the foreseeable future, there is likely to be enough competition in the dial-up market to ensure that Time Warner's rivals get fair exposure on the Internet and that AOL is not tempted to raise dial-up subscription prices too high.

The merger's critics also worry that AOL may use Time Warner's muscle in the cable market to drive out competitors. Roughly a fifth of the cable going into American homes is owned by Time Warner, and increasingly those cables will be used to deliver high-speed Internet access as well as traditional TV shows. Now that AOL is set to own this infrastructure, it could theoretically bar cable customers from signing up with rival Internet dial-up services.

Again, the merging companies insist that they do not intend this. They say that Time Warner's cable customers will be free to buy Internet access from the full range of competing dial-up providers. This is another promise of an "open strategy" that should be watched. AOL will doubtless avoid a crude exclusion of dial-up rivals from its cable network, since that would invite regulatory intervention. Subtler arrangements are what must be guarded against. But even if AOL sought to use its ownership of cable to tilt the market for dial-up services in its favor, customers would be left with real choices: They could buy high-speed Internet access from phone companies or from satellite firms.

Down the road, there may be reasons to fear the muscle of AOL Time Warner, assuming that the deal does go ahead. But our sense is that in the near future the new company does not endanger consumer choice or competition. Federal regulators, who have chosen to tread lightly around the Internet, should not feel pressured by the creation of this giant to rethink their approach.