balance of power

[masterding]

Quote from VOA:
"The U.S. Congress has an image problem. Americans overwhelmingly view lawmakers as privileged.
...
And while House Speaker John Boehner and former Speaker Nancy Pelosi have faced media scrutiny for stock trades, the U.S. Securities and Exchange Commission has avoided investigating lawmakers' financial dealings.

Washington investment manager and author Michael Farr says financial markets are damaged when the presumption of a level playing field for all is eroded:

"When one group suspects that the other group has an advantage, then all of a sudden the balance of power shifts," said Farr. "That changes prices, and it certainly keeps participants away. Fairness encourages more participants.""

What does "balance of power" mean?

Thanks.