The meanings of "fruition" are "fulfilment, the realization of aims".

I think this might be a good possibility.
The Maot definition defines it in business as converting goods for cash, your added context: כשמשקיע בקרן פודה את כספו...
the verb redeem works there (when an investor redeems....)
so I think the noun could work for מימוש.

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Note added at 23 mins (2011-10-09 10:42:49 GMT)
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http://www.investorwords.com/4103/redemption.html
http://www.investopedia.com/terms/r/redemption.asp#axzz1aHOZ...

I can't be sure without more clear cut context, but I think this is a possibility if the general meaning of "redeem/redemption" is being invoked (that of exchanging goods/cash or getting something back).

Hope this helps.

מִימוּשׁ רְוָוחִים
לועזית: profit realization / take profits
1. מכירה של מניות כאשר יש עלייה בשערן מעל למחיר הרכישה, ובכך להפוך רווחי נייר לרווחים ממשיים 2. בניתוח מגמות המסחר בבורסה: גל מכירות הפוקד את המסחר בבורסה בעקבות עליות בשערי ניירות ערך.

מילון מעות

Sell-off is not exactly "מימוש", but "The rapid selling of securities, such as stocks, bonds and commodities. The increase in supply leads to a decline in the value of the security.if a company issues a disappointing earnings report, it can spark a sell-off of that company's stock. Sell-offs also can occur more broadly.

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Note added at 3 hrs (2011-10-09 14:12:24 GMT)
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There are more cases of "realization" and "exercising," the difference lying mainly in the nature of realization which usually results in changing a non-liquid asset into a liquid asset, and exercising, which consists of applying an optional right to a transaction.

מימוש is often simply "sell" or "sale" which is the short way of expressing "conversion of goods for cash". As always, it depends on context.

In the case of stock options, the term is vesting. If you are given the options as an employee of a company, at a certain point you have the right to vest them, which is to buy them at a fixed price. You can later sell them at their market value.