By Douglas A. McIntyre, 24/7 Wall St.

Critics find fault with Amazon.com (AMZN) for many reasons, among them: the e-commerce company's penchant for offering free shipping that damages margins; its entry into too many many businesses, including video on demand; and concerns it may be selling some of its Kindle products at a loss in the hopes of selling books or software for the device later. 

However, none of these perceived shortcomings have perturbed Amazon's base of enthusiastic stockholders.

Amazon's share price has risen from just above $220 before Thanksgiving to $254. That has outperformed the Nasdaq over the same period, and topped shares of the two companies that by almost all measures have the largest online visitor bases after Amazon -- Wal-Mart Stores (WMT) and Target Corp. (TGT). Amazon's growth for the current quarter will have to be spectacular to justify the run-up.

Analysts expect Amazon's revenue in the current quarter to reach $22.5 billion, up from $17.4 billion in the same period a year ago. The e-tailer's sales improvement record would justify the estimates, but forecasts for net income are another matter. Many analysts expect per-share earnings to be flat at around $0.38. That level would seem to be a disappointment, but Amazon's share price says otherwise.

Investors seem content for now that widely regarded founder and CEO Jeff Bezos has made a reasonable trade-off between top line growth and a sacrifice of earnings to keep a torrid pace of revenue improvement. There will be a tipping point among Wall St. investors, though, when they believe the earnings sacrifice is too great.

That tipping point has not yet come. But if per-share earnings show a sharp drop in the current quarter because of Bezos's strategic plan to gain market share, the share price improvement will end.

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