You can't add returns like that. Each year is cumulative/compounding. At the end of the three years, your investment is down to 0.909 * 0.88 * 0.777 ~= 0.6215, so you've actually lost 48%, not 43%.
Lookup arithmetic vs geometric investment returns for more info.
To really drive the point home, consider the following thought experiment: let's say you have a catastrophic -99.99% return the first year, then a solid 9.74%[1] return for each of the next 99 years. The arithmetic average return is (-0.9999 + 99*0.0974)/100, or about 8.6%, which sounds pretty good. But the geometric (i.e. actual) trajectory of your money is that you started with $1000, went down to $1, and then slowly grew back to exactly $1000! So your actual 100-year return was 0%.
[1] Use the 99th root of 10000 for the exact value needed to make this example work.