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The Dow Jones Industrial Average (DJINDICES:^DJI) is up as markets continue their relentless surge forward. The DJIA is being pulled up by the financial sector, as Federal Reserve chair-designate Janet Yellen's confirmation hearing yesterday reinforced investors' views that the Fed's stimulus policies will continue. However, ExxonMobil (NYSE:XOM) is the Dow's leader today after it was reported that Warren Buffett had taken a $3.5 billion stake in the oil major.

As of 1:33 p.m. EST the Dow was up 44 points to 15,920. The S&P 500 (SNPINDEX:^GSPC) was up two points to 1,793.

Speaking yesterday before the Senate Banking Committee, Yellen said she wants to see a self-sustaining recovery before the Federal Reserve eases up its stimulus efforts. She noted: "A strong recovery will ultimately enable the Fed to reduce its monetary accommodation and reliance on unconventional policy tools such as asset purchases. I believe that supporting the recovery today is the surest path to returning to a more normal approach to monetary policy." All signs indicate that Yellen will continue the policies of current Chairman Ben Bernanke, meaning a zero-interest-rate policy and continued large-scale asset purchases.

Yellen suggested an addition to the Federal Reserve's dual mandate of full employment and low and stable inflation: "a safe and sound financial system." Regulators around the world have pursued this by increasing capital requirements for banks, as well as requiring yearly stress tests. However, the problem of too-big-too-fail banks still persists, and it is unclear what unintended effects are being created by the Fed's continued stimulus and rising balance sheet, now at $4 trillion. As the U.S. financial system grows further centralized around the Fed, the risk of a shock to the system doing real damage increases.

While many investors are sitting on the sidelines, there was news today that Warren Buffett has bought a 40 million-share stake in ExxonMobil. This is Berkshire's largest outright purchase since it invested $10 billion in IBM in 2011. While that's a big investment, Berkshire's total portfolio is worth roughly $100 billion, so this is a just a 3% position within those holdings.

Dan Dzombak can be found on Twitter @DanDzombak or on his Facebook page, DanDzombak. He has no position in any stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.