With the $1.1 billion acquisition of Tumblr, Yahoo is putting a serious claim in for the future of social and mobile technology. Whether it turns out to be a boon or a bust for Yahoo shareholders, the deal will be one of the biggest tests for chief executive Marissa Mayer's leadership.

Let's start with the obvious point. The purchase price is a lot of money. Yahoo is not getting Tumblr on the cheap. At $1.1 billion, the company will be spending about one-fifth of the cash and short term investments it had at the end of its last quarterly statement. This is a big bet for Yahoo.

The six best math students at the all-boys Browning School on Manhattan's East Side were given bad news, and then worse news. Their math teacher had suffered a heart attack and would not be returning to teach—that was the bad news. The worse news was that her replacement did not know calculus.

If the students wanted to continue to study calculus, they would have to teach it to themselves.

Three of the students decided the task was hopeless. The other three stuck it out. They'd go to class each day and work through the problems in their textbooks. There was no teacher in the classroom at all. Just the three students, trying to teach themselves one of the most bedeviling subjects a high school student ever faces.

One of the students who kept up with calculus was Jamie Dimon, the guy who would eventually become the chief executive officer and chairman of the board of the largest bank in the country, JPMorgan Chase. At the time, math was not even his favorite subject—that was history—but it was his strongest.

You might think that the administrators and teachers at Browning would be deeply impressed by this academic dedication. But you would be wrong about that. Even though he graduated fourth in his class, Dimon was rejected by Brown University—in part because of a backhanded recommendation letter written by the assistant headmistress of the school.

"His lack of manners, due to his habits of making quick judgments and contradicting others, is greatly improved," the assistant headmistress wrote, according to Duff McDonald's biography of Dimon, Last Man Standing (from which this school days tale is lifted).

She praised Dimon's "keen, analytical mind" and his "dedication and seriousness of purpose." But she could not avoid mentioning what she saw as his problem with authority. Dimon was too headstrong to win her unqualified praise.

Forty years later, Dimon once again finds himself pitted against the corporate governance equivalent of a legion of assistant headmistresses. A pair of influential shareholder advisory groups, Institutional Shareholder Services (ISS) and Glass Lewis, have recommended that shareholders vote to split Dimon's role as chairman and chief executive. The AFSCME Employees Pension Plan, the Connecticut Retirement Plans & Trust Funds, Hermes Equity Ownership Services and various New York City pension funds have issued a shareholder proposal calling on JPMorgan Chase to name an independent chairman.

Whatever course it chooses, the Federal Reserve will have to grapple with the reality that while its policies have helped levitate stocks, they've been considerably less effective at expanding the economy.

While rising equity prices help add to total growth, the stock market is not the economy.

The U.S. economy, rather, is propelled by consumption, which accounts for about 70 percent of gross domestic product.

That consumption in turn, is generated by wealth, and the signs are growing that benefits of a skyrocketing stock market have been disproportionate.

"We've made rich people richer," Dallas Fed President Richard Fisher told CNBC in a Monday interview.

High fees plus poor performance: The formula is pretty easy to determine what makes a bad mutual fund.

Some, though, are worse than others—and some are so bad that they've made it into one publication's unofficial hall of shame for charging big fees but delivering small results.

Funds that depend on bad market performance—"bear funds"—for their growth have done particularly poorly, as have those in precious metals.

Wall Street's stock market mania officially has gone full-throttle.

JPMorgan took the lead Friday in the battle of the bulls, raising its year-end price target for the Standard & Poor's 500 to 1,715. That's a big leap from the firm's original projection of 1,580, which the index blew through on April 24.

The forecast is the highest call among Wall Street strategists, who are uniformly optimistic about the market's prospects this year.

Joe Weisenthal is quite harsh on Michael Kinsley's latest attempt to defend "fiscal discipline" (the policy formerly known as austerity), writing that the famed editor and columnist has "humiliated himself."

What happened is that Kinsley responded to an essay by Paul Krugman titled "Austerity Kills" with a piece in The New Republic titled "Paul Krugman's Misguided Moral Crusade Against Austerity."

Near the end of the piece Kinsley writes: "I don't think suffering is good, but I do believe that we have to pay a price for past sins, and the longer we put it off, the higher the price will be."

Don't expect Moody's to downgrade Berkshire Hathaway.

Standard & Poor's on Thursday took its counterparty credit rating on Berkshire Hathaway down by a notch, to AA from AA Plus.

The cynics in our midst immediately cast smirks in the direction of Moody's, which just happens to have a chunk of stock (11.5 percent) owned by Berkshire. Would the credit raters at Moody's have the temerity to downgrade their patron Sage of Omaha?

Wall Street's stocks-are-cheap meme looks as if it will start coming under stress if what one firm calls a "profitless rally" continues.

Stocks have rallied more than 30 percent on a global basis since the 2011 slows, though earnings per share have been flat, according to Citigroup.

That was easy to do, as stocks traded at only about 12 times earnings in the depths of that market. But with prices pulling further away from their flatlining earnings numbers—the vaunted P/E ratio—investors may have to temper their expectations for the accelerating markets.

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"We expect markets to make further gains supported by moderate EPS growth and dividend increases," Citi analysts said in a report that warned about the "profitless rally." But "valuations imply less impressive gains from here," they said.

A data terminal company. A newswire. A broker-dealer.

Bloomberg is all of these things. But did you know Bloomberg is also now a registered investment advisor?

Bloomberg Wealth, which does business under the name BloombergBlack, is not yet a big operation. It employs just 33 people, only nine of whom perform investment advisory functions.

There's a twitter account @bloombergblack but it's never tweeted, follows no one and has only 11 followers (I wasn't able to confirm that this belongs to the brokerage). And there's a blog with some relatively banal market news and investment advice.

Odds are that many Wall Street customers of Bloomberg have never even heard of BloombergBlack. Certainly Bloomberg's marketing so far has been very quiet, perhaps because it feels a little awkward about going into business in competition with the people who pay $20,000 a year for Bloomberg terminals.

But it is definitely up and running as an online wealth management company—kind of. It's more or less in beta, as the tech folks say. Right now BloombergBlack is only accepting a "limited number of investors." You have to request an invite—and you can't even put in a request unless you have somehow received a referral code. If accepted, you'll get a 60-day free trial. After that the service will cost you a hundred bucks a month.

What's the service?

Third Point's Dan Loeb is becoming something of a media mogul it seems. He's held Yahoo for ages. He owns a stake in Virgin Media. He's in Sony. And now he's buying a piece of Metro Goldyn Mayer, according to The Hollywood Reporter.

THR writes:

Loeb has apparently been acquiring shares on the private market in the closely-held movie and TV company, most recently at a price of about $50 a share -- a 78 percent increase over the price a month ago of $39 a share. That, in turn, is about double what MGM traded for a year earlier, shortly after it came out of a pre-packaged bankruptcy.

Loeb had no comment, and it's unclear how many shares of MGM stock he's bought. MGM's private stock currently trades for $51 a share.

The rumor on MGM is that the company is planning to raise capital in the near future, perhaps through a private placement. Because IPOs are so uncool these days.