While working at IBM I accumulated a fair amount of IBM stock through their employee stock purchase plan (ESSP). Left to my own devices I would have probably held onto to it indefinitely despite the risk from lack of diversification. However my new employer perceived a conflict of interest issue and I was required to sell most of my stock (I was allowed to and did retain a small amount). In order to do this I opened an account with a discount broker and transferred my stock into it. I was given 4 years to sell my stock but ended up selling about a quarter in late 2011 and then most of the rest in late 2012 (to avoid the federal tax increases effective in 2013).
Since I was comfortable with this money in the stock market the sensible thing to do would have been to buy an index ETF as I sold the IBM. Instead I decided to pick stocks myself. This didn't work out too well. Because I didn't get around to actually picking some stocks the money from the 2011 sales sat in my broker's money market account earning next to nothing through most of 2012 while the market (by which I mean the S&P 500) was up over 15%. At the end of 2012 I finally managed to actually buy some stocks (and I did put a big amount into an index EFT as I realized at the slow rate I was picking stocks the money was otherwise likely to remain idle for some time). Still I entered 2013 with over 30% of this money in cash. I did buy more stocks (and some specialized index ETFs) throughout the year so by the end of the year my cash position was under 10%. The result was in 2013 my brokerage account was only up 20.5% while the market was up 32%. This shortfall was mostly due to not being fully invested but my individual stock picks generally lagged the market as well. On the brighter side they did better than IBM which was one of the few stocks to be down (slightly) in 2013. So being forced to sell IBM may turn out okay.
The main lesson I draw here is that picking your own stocks in addition to the obvious drawbacks can have a somewhat hidden cost in the form of delays in getting your money into the market. Of course this delay won't usually be as costly as it was in 2013 and in a down year would actually benefit you. Still having made the correct decision to keep my money in the market it is too bad I didn't implement it better.