When deciding whether to buy, sell, or hold a stock, investors often rely on analyst recommendations. Media reports about rating changes by these brokerage-firm-employed (or sell-side) analysts often influence a stock's price, but are they really important?

Let's take a look at what these Wall Street heavyweights have to say about Novo Nordisk (NVO) before we discuss the reliability of brokerage recommendations and how to use them to your advantage.

Novo Nordisk currently has an average brokerage recommendation (ABR) of 1.60, on a scale of 1 to 5 (Strong Buy to Strong Sell), calculated based on the actual recommendations (Buy, Hold, Sell, etc.) made by 15 brokerage firms. An ABR of 1.60 approximates between Strong Buy and Buy.

Of the 15 recommendations that derive the current ABR, 11 are Strong Buy, representing 73.3% of all recommendations.

Brokerage Recommendation Trends for NVO

Check price target & stock forecast for Novo Nordisk here>>>

The ABR suggests buying Novo Nordisk, but making an investment decision solely on the basis of this information might not be a good idea. According to several studies, brokerage recommendations have little to no success guiding investors to choose stocks with the most potential for price appreciation.

Are you wondering why? The vested interest of brokerage firms in a stock they cover often results in a strong positive bias of their analysts in rating it. Our research shows that for every "Strong Sell" recommendation, brokerage firms assign five "Strong Buy" recommendations.

In other words, their interests aren't always aligned with retail investors, rarely indicating where the price of a stock could actually be heading. Therefore, the best use of this information could be validating your own research or an indicator that has proven to be highly successful in predicting a stock's price movement.

With an impressive externally audited track record, our proprietary stock rating tool, the Zacks Rank, which classifies stocks into five groups, ranging from Zacks Rank #1 (Strong Buy) to Zacks Rank #5 (Strong Sell), is a reliable indicator of a stock's near -term price performance. So, validating the Zacks Rank with ABR could go a long way in making a profitable investment decision.

ABR Should Not Be Confused With Zacks Rank

Although both Zacks Rank and ABR are displayed in a range of 1-5, they are different measures altogether.

Broker recommendations are the sole basis for calculating the ABR, which is typically displayed in decimals (such as 1.28). The Zacks Rank, on the other hand, is a quantitative model designed to harness the power of earnings estimate revisions. It is displayed in whole numbers -- 1 to 5.

It has been and continues to be the case that analysts employed by brokerage firms are overly optimistic with their recommendations. Because of their employers' vested interests, these analysts issue more favorable ratings than their research would support, misguiding investors far more often than helping them.

In contrast, the Zacks Rank is driven by earnings estimate revisions. And near-term stock price movements are strongly correlated with trends in earnings estimate revisions, according to empirical research.

Furthermore, the different grades of the Zacks Rank are applied proportionately across all stocks for which brokerage analysts provide earnings estimates for the current year. In other words, at all times, this tool maintains a balance among the five ranks it assigns.

Another key difference between the ABR and Zacks Rank is freshness. The ABR is not necessarily up-to-date when you look at it. But, since brokerage analysts keep revising their earnings estimates to account for a company's changing business trends, and their actions get reflected in the Zacks Rank quickly enough, it is always timely in indicating future price movements.

Should You Invest in NVO?

Looking at the earnings estimate revisions for Novo Nordisk, the Zacks Consensus Estimate for the current year has declined 0.4% over the past month to $3.87.

Analysts' growing pessimism over the company's earnings prospects, as indicated by strong agreement among them in revising EPS estimates lower, could be a legitimate reason for the stock to plunge in the near term.

The size of the recent change in the consensus estimate, along with three other factors related to earnings estimates, has resulted in a Zacks Rank #4 (Sell) for Novo Nordisk. You can see the complete list of today's Zacks Rank #1 (Strong Buy) stocks here >>>>

Therefore, it could be wise to take the Buy-equivalent ABR for Novo Nordisk with a grain of salt.

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