In a 401 k plan, when they say that an investment is 100%conservative and is under only one fund...?

what is that mean allso says 100% stability of the principal, and what is a diversification, and how can I find out what other options do I have, and what is the benefit of such diversification, please advise thank you and have a nice day!!!

The way that you described it is not totally clear,but:

Diversified just means that your funds are spread over more than one type of asset. This could mean more than one type of stock, or stocks plus bonds, or other types of assets.

We cannot know what the options are in your 401k, since those differ from company to company.

For your specific investment that you're looking at, the best thing to do is to read the prospectus. (You can always get a copy of this from the fund company or the company administering your 401k.)

If you have a fund name or ticker, or if you have a list of the funds available in your 401k, feel free to re-post your questions with that detail and you will probably get more useful feedback.

Not enough info to answer. A typical 401(k) plan provides a variety of investment options ranging from aggressive to conservative. You must pick the allocation among these that fits your needs and desires. See www.401k.org or investopedia.com for more info.

There should be some one in human resources where you work that can tell you what your options are. Each company is different. Remember, your company does not control the 401K. It is handled by a company such as Fidelity. 100% of stability of the principal would usually be CDs. Conservative funds are usually large cap funds or indes funds. Diversification means that your shares are spead over a larger amount of different stocks, bonds and indexes. You won't make as much in an up market, but you won't lose as much in a down market. Depending on your age, the younger you are the more agressive you can be. Do not be agressive within 5 years of retiring.

For an IRA you should be ~40% & ~40% in US and Int'l stock funds with just a small percentage in bond funds.

You likely have 30+ years for stock funds to go up and outperform your bond funds...

Don't try to time the market cause most people end up selling stock funds when they are low and then end up buying them high.