The US government has interceded and intervened in markets many times before, including some bailouts to prop up a market and/or to prevent it from collapse.
Historically, that had occurred in 1792, when the US government bailed out the 13 United States (from Revolutionary War debt), and has continued many times, including in the Great Depression, the S&L bailout of 1989, and in the collapse of Bear Stearns, and also those of Freddie Mac and Fannie Mae. (Woods, 2009).
Most of these bailouts were necessary, and many were efficient.
Let’s highlight the US government bailout of AIG in 2008 as efficient, but also illegal.
AIG (American Insurance Group) had bought CDSs on CDOs, insuring $441 billion of assets, but as the value of the structured debt securities backed by subprime loans declined, AIG’s credit rating was downgraded, leading to a liquidity crisis, and the US government quickly stepped in with a secured credit facility of $85 billion, secured by warrants for ~80% of AIG and its subsidiaries. (Barofsky, 2012)
The bailout was efficient since the US government got all its money back and even made $20 billion+. (Woods, 2009)
However, taking control of 80% of AIG, and expelling its chief executive, may not have been legal, and certainly was draconian (Barofsky, 2012), and in fact a recent court ruling on this issue (U.S. District Court, Southern District of New York, No. 13-00951) was that “On the face of it” some of the government’s actions “perhaps are unattractive and, indeed, wrongful.” Further, Judge Thomas Wheeler (the US Court of Federal Claims) ruled that the actions of the Federal Government were illegal.
Nevertheless, had the US government not intervened, AIG would likely have quickly gone in to bankruptcy, having a major effects on markets around the planet.
As far as inefficient government interventions are concerned, in the UK the government came up with a Growth Voucher Scheme to help Small and Medium sized Enterprises, but only 7000 firms instead of 20000 used the vouchers, spending £3.6m out of £30m.
There are, of course, hundreds or thousands of examples in the US, as well.
References:
Barofsky, N. (2012). Bailout: An inside account of how Washington abandoned Main Street while rescuing Wall Street. New York: Free Press.
Woods, T. (2009). Meltdown: A free-market look at why the stock market collapsed, the economy tanked, and government bailouts will make things worse. Washington, DC: Regnery Pub.