Amazon.com Inc. investors should be warned that Wall Street may be a bit complacent on the e-commerce and cloud giant’s stock, ahead of the first-quarter earnings report due out after Thursday’s close.

For one, the stock options market is prepping for a one-day post-earnings move that is less than that day’s average over the past five years, as well as the most recent quarters.

And all 45 of the analysts surveyed by FactSet are bullish on the stock for the past month.

There’s an old Wall Street adage that if everyone is leaning in the same direction, it’s better to bet in the opposite direction. As famed economist John Maynard Keynes supposedly explained, the central principle of investment is to go against the general opinion, because if everyone is bullish, that investment is inevitably expensive and therefore unattractive.

And on a short-term basis, the idea is that if you’re bearish and wrong, the stock won’t run too far against you, because everyone has already bought the stock; if you’re right, the bang-for-the-buck will be greater because sellers may have a hard time finding a buyer since everyone had already bought, which could result in a bigger-than-warranted selloff.

Don’t miss: Amazon earnings: Revenue comes into focus in 2019.

But it’s not easy to find someone who says those warnings apply to Amazon’s stock, which contrarians might say is a warning in itself. Either way, there is a reason for investors to expect to be surprised.

An options strategy referred to as a “straddle,” which is a pure volatility play that involves the simultaneous purchase of bullish (calls) and bearish (puts) with identical at-the-money strike prices, was prepping for a 4.1% move in the stock in either direction on Friday. Read more about options straddles ahead of earnings.

That means based on current levels — the stock AMZN, -4.12% rallied 0.7% Thursday afternoon to $1,914.76 — buyers of the straddle will start making money if the stock rallies above $1,994.04 or if it falls below $1,835.48.

While that might seem like a wide spread for such a mega-capitalization stock, over the past 20 quarters, the average one-day post-earnings move has been 6.7%, with the average on 11 gaining days of 6.8% and the average on nine declining days of 6.6%. The past two quarters, the stock shed 5.4% and 7.8%.

And after KeyBanc Capital analyst Edward Yruma upgraded Amazon to overweight last month, the bullish calls became unanimous, with all 45 analysts surveyed by FactSet rating the stock the equivalent of buy.

FactSet, MarketWatch

The average price target is $2,128.32, which is about 11% above current levels.

But as some analysts have pointed out, it’s not like the bullish consensus is a sudden phenomenon. At least 90% of the ratings have been bullish since October 2017, with the non-bullish ratings being neutral, or hold. There hasn’t been a bearish sell, or underweight, rating on the stock since September 2017.

“Clearly, Amazon is and has been a consensus long for a good long time,” said Art Hogan, chief market strategist at National Securities Corp. “I’m not sure in this particular case that we need to be overly concerned about 100% of analysts covering the name having rated that we’re near a buy.”

And Ari Wald, head of technical analysis at Oppenheimer, said the bullish call on Amazon is two-fold: From top-down, as macroeconomic conditions and a flat yield curve favor large-capitalization growth stocks, and from bottom-up, given a bullish long-term technical foundation.

So regarding potential worries that everyone is already bullish?

“I don’t know how reliable that is as a value-added signal,” Wald said. “It’s the most tactical Amazon has been in a number of years.”

From a technical perspective, the weekly moving average convergence-divergence indicator (MACD), known affectionately as Mac-D, has flashed a buy signal starting from negative territory for the first time in years, since early 2015 according to FactSet.

FactSet, MarketWatch

(Read more about MACD buy signals, when they appeared in Facebook Inc.’s FB, -2.24% and Twitter Inc.’s TWTR, +6.08% charts.)

In addition, a bullish “golden cross,” in which the 50-day moving average crosses above the 200-day moving average, is on track to appear after Thursday’s close. That would suggest, many technicians might say, that the bounce off the December lows has graduated to a longer-term uptrend. Read more about the bullish “golden cross.”

FactSet, MarketWatch

Bottom line, with everyone expecting a bullish earnings report, there is a risk that the crowd is set up for disappointment, even if Amazon beats earnings and revenue expectations, like last quarter, but that by itself isn’t a reason to bet against the crowd. “They’re going to be right the whole way up, and be wrong once,” Wald said.

FactSet, MarketWatch

Keep in mind that last quarter’s disappointment was relatively short-lived, as the stock was recently trading 11% above where it was before the fourth-quarter report was released.

Basically, Wall Street may be following another adage that is less known to the public: If you have to lose money, it’s better to do so when everyone else is losing than when everyone else is winning.