Complex sentence: Suppose further that the investor is advised by his broker or financial advisor that Technology should be "overweight" then, the investor is being advised to hold more investments in Technology, as a percentage, than the weight of that asset in the index/market.
Split into simpler sentences: Suppose further that the investor is advised by his broker or financial adviser that Technology should be "overweight". The investor is being advised to hold more investments in Technology, as a percentage, than the weight of that asset in the index/market.