* Fed Chair Yellen testifies before Congressional committee
* IMF to cut U.S. growth forecast for 2016
* Nike drops on disappointing future orders
* Indexes down: Dow 0.12 pct, S&P 0.18 pct, Nasdaq 0.21 pct (Updates to early afternoon)
By Yashaswini Swamynathan
Sept 28 (Reuters) - Wall Street was lower on Wednesday as health stocks weighed and financials fell after Federal Reserve Chair Janet Yellen said the central bank was considering changes to the annual stress test.
Yellen said the Fed was looking at a more risk-sensitive, firm-specific approach to the test that would raise capital requirements for big U.S. banks based on their test results.
Shares of JPMorgan, Bank of America and Citigroup were down between 0.2-0.5 percent.
Healthcare sector weighed the most on the benchmark S&P 500 index as Bristol-Myers and Amgen fell 1.2 percent each. The index had risen 0.7 percent on Tuesday.
Adding to the downbeat market sentiment was the lowering of the 2016 U.S. growth forecast by the International Monetary Fund.
"I think what we are seeing today is really a lot of noise," said Terry Sandven, chief equity strategist at U.S. Bank Wealth Management in Minneapolis.
At 12:31 p.m. ET (1631 GMT), the Dow Jones Industrial Average was down 21.71 points, or 0.12 percent, at 18,206.59.
The S&P 500 was down 3.94 points, or 0.18 percent, at 2,155.99.
The Nasdaq Composite was down 11.36 points, or 0.21 percent, at 5,294.35.
Ten of the 11 major S&P 500 indexes were in the red, with telecom services falling the most with a 1.4 percent drop.
AT&T's 1.9 percent fall weighed the most on the sector. The stock was downgraded to "neutral" by UBS. Rival Verizon was down 1 percent.
The energy index was set to have its best day in a week on speculation that OPEC members gathered in Algeria could lay the foundation for a deal to limit output.
Nike dropped 3.1 percent and was among the top drags on the S&P and the Dow after the shoemaker's orders missed analysts' estimates for the third time in a row.
Paychex dropped 4.5 percent after the payroll processor lowered its full-year profit forecast.
Advancing issues outnumbered decliners on the NYSE by 1,600 to 1,29. On the Nasdaq, 1,454 issues fell and 1,211 advanced.
The S&P 500 index showed 12 new 52-week highs and three new lows, while the Nasdaq recorded 71 new highs and 31 new lows. (Reporting by Yashaswini Swamynathan in Bengaluru; Editing by Anil D'Silva)