For the inexperienced asking about 401k/IRA asset allocation

Info in another article regarding why it shouldn't have been a lost decade of investing through 2010:

Bucks

"The lost decade claim starts with the assumption that whenever we talk about investing, we’re talking about owning just American stocks, often using the S.&P. 500-stock index as the proxy for our investment experience."

"Then we just sat there. We did nothing! No rebalancing, no rethinking. Nothing.

The return for this diversified stock portfolio for the same 10-year period was an annualized 8.35 percent. That is a far cry from a lost decade.

It’s also worth noting that earning the 8.35 percent annualized return would have required behaving and not reacting badly during a painful 2008 and early 2009. Resisting the temptation to get out during that period was the cost of earning the 8.35 percent.

That said, most real people wouldn’t (or shouldn’t) have all of their long-term money invested in stocks even if they’re broadly diversified among many different indexes. So what happens if we add bonds to our long-term portfolio to act as ballast to the equity exposure?"

Bold added.

"So we build a portfolio that looks like this:

60 percent equities (evenly split among our five categories)
40 percent fixed income (Barclays U.S. government intermediate-term index)

The 10-year annualized return for this portfolio was 7.83 percent. Again, that’s a far cry from a lost decade."

Pretty powerful stuff even though it is hurry up and wait. Tactically investing and/or rebalancing your assets during large gap downs could have benefited you even more. No guarantees, but it doesn't get any easier than that.