Offer - what are your thoughts?

Received an offer to consult/work for a micro-fund ($5 mil) for 48k a year, but the pm has expensed it as part of the "bonus".

the wording says 20%, but the trading profits paid to Y, is 20%. so effectively that is about 4%. (20% of 20%)

Employee will be eligible to share in trading profits paid to Y by X. Employee shall receive a $4000.00 monthly draw which will accumulate as an
expense against the year end “Special Bonus.” The payment is not a loan. Employee will be
entitled up to twenty (20) percent of total bonus compensation paid to Y
by X. Employee shall receive a monthly trading statement from Employer. Payment shall be calculated based on total profitability at December 1, 2013, and each December
1 thereafter. Fifty (50) percent of the twenty (20) percent shall be paid to Employee within Sixty
(60) days of December 1. Fifty (50) percent of the bonus up to a maximum of $250,000.00 shall be part of the “holdback” and vest over the following year.

is this fair? The language "up to twenty (20 percent" ("up to" rather than a solid 20%) seems weird. no benefits, but I'm able to telecommute.