They have a 25% limit of your account balance can be invested in "Tradelink" account (via T.Rowe Price). However, as the price/value of MCCY/EFFC has plummetted downward since I first started investing in my 401K, that portion kept going below 25% of my balance and I was able to keep transferring more in, and so on and so on. It's either a huge blessing I was able to do this, or the start of a serious gambling addiction. :-)