"Jeremy Siegel on ‘Dow 15,000’"

It appears the old perma-bull is right this year.
I don't have much time* for professor Siegel, he doesn't seem to have a very flexible mind and his methodology is suspect.
He is however a tenured professor at Wharton so someone thinks as highly of him as he does of himself.
From Advisor Perspectives:

Many people worry that market prices are artificially elevated now because of Fed policy or that our excessive debt will eventually force prices lower. What advice would you offer to those investors?

The prices of bonds are being sent artificially high, and that is where the real concern is. We’re in the biggest bond bubble in history right now, even greater than the bond bubble right after World War II, when rates were also kept artificially low. The danger is definitely on the bond side, with stocks still selling below 15-times earnings. Earnings estimates for this year look pretty much like 100 per share, and for next year operating earnings look like 105 to 107 per share.

For those people who ask, “Well, what happens if interest rates go up?” one should remember that bull markets are never killed at the beginning of an interest rate up-cycle. Those markets usually go on for many months if not years after the increase in rates. Only when rates get very high and the squeeze gets very hard does that signal the end of the bull market, so I do not fear higher rates. In fact, if the Fed forces higher rates, in my opinion that’s a sign that they think the economy is improving and it would actually be a favorable sign for the market.

Profit margins are not high, and I challenge Jeremy Grantham to say why they are high.  He said they were high two years ago. That was one year out from the worst recession. Unemployment was high. There were a lot of unsold goods. There was very little pricing power.  Now, he’s not telling us why they are unusually high. I can understand them being high at the top of a business cycle. Clearly, where there is a boom in demand, firms can get almost any price that they ask when there are shortages of certain goods, but why would there be artificially high profit margins coming off the worst recession in 75 years?.

Corporate profits are up about 8.7% since a year ago, and reported earnings per share for the S&P 500 are at an all-time high. To some degree, this has distorted Shiller PEs to the upside, whereas there was a downside distortion during the financial crisis in 2008, as you have correctly pointed out. Now, Jeremy Grantham of GMO has warned that profits are eventually going to revert to the mean, at least over the long term, and he uses a seven-year time horizon. What is your feeling about an eventual reversion to the mean for profit margins and corporate profits?

You’ve got to be very careful about that. Profit margins are high, but they’re not at an all-time high.  There are two very good reasons why profit margins are high. One is because the percent of profits coming from foreign sales is a steadily increasing fraction, and the margin on foreign sales is higher, probably because the tax rate on foreign sales is lower. It’s often been advertised that our corporate tax rate is the second-highest in the world. In fact, even Obama has proposed lowering our corporate tax rate. So one of the reasons the margin is high is foreign sales.

Another is the growing importance of technology sales, which automatically have higher margins because of the way accountants expense R&D. It looks like they’re getting higher margins because of the fact that so much of their cost structure is in development costs.  It looks like their margins are high. Technology is going to continue to be a strong part of the S&P, so I don’t see that reverting to mean nor do I see foreign profits reverting immediately to the mean.

So I’m very skeptical that we’re going to get a big reversion of profit margins to the mean.  They’re high, and they’re going to stay higher than normal. Corporate profit as a percent of GDP is distorted because more firms are being classified in the corporate sector and less in what’s called proprietors’ income or private income. The return on total capital, both public and private, is not rising as a percent of GDP. What we see rising as a percent of GDP is corporate, because more firms are incorporating and we have less proprietors’ income than we used to in the economic data....MUCH MORE

Siegel uses stock market data going back to 1801. For reasons ranging from survivor bias (e.g. no canal stocks made it) to sample size to over-representation of banks to a dearth of dividend information to....
...you can probably tell I traveled this road during a misspent youth. See:
Does Stock-Market Data Really Go Back 200 Years?

For the mental flexibility problem see the May 29, 2000 BusinessWeek article:
The Great Market Bubble Debate

...Siegel: Seven percent per year [average] real returns on stocks is what I find over nearly two centuries. I don't see persuasive reasons why it should be any different from that over the intermediate run. In the short run, it could be almost anything....

It's actually 6.8%, a number Bill Gross refers to as the "Siegel Constant".
Here's what the Nasdaq did from it's 5048 high in March 2000:
 

The naz just hit 3222, a number CNBC informs us is "Highest Since November 2000"
That is still a long way from 5048. Siegel never saw the bubble.

Here's another one:
Jeremy Siegel Says Get Ready to Buy

The "Wizard of Wharton" says don't worry. "If investors have cash on the sidelines, they should not wait too long to put it to use," says Jeremy Siegel, Wharton business school professor at the University of Pennsylvania and well-known markets commentator. "There are good values out there in equities -- especially in financial stocks -- and you will be rewarded in the long run if you start dollar cost-averaging now.">>>MORE

That was dated August 10, 2007, 60 days before the market's all-time highs.
Meaning 60 days before the start of the most devastating decline in equity values that anyone born in the last 76 years has ever seen.
Morever, he specifically pointed to the absolute worst segment of the market as having good values.
Good values?
More like Good Grief.

So I don't have much time for the good professor.

CNBC seems to love him theough:
 http://www.cnbc.com/id/48975990/Jeremy_Siegel_Dow_17000_lsquoVery_Very_Attainablersquo
http://www.cnbc.com/id/46998860/Jeremy_Siegel_Dow_Could_Hit_17000_Next_Year
http://www.cnbc.com/id/46892956/Wersquoll_See_Dow_17000_in_2013_Jeremy_Siegel