Cowrie-shell radical at the bottom — shells were ancient currency, so it indexes money characters like 财 wealth, 账 account, 赔 to compensate. Under a stooped person, the shells become a debt or burden one carries: hence the senses 'owe, lose, suffer a loss, negative.'
semantic
⺈dāo
person bending over (here)
Top is a contracted form of 人 'person' bending forward, the same bent-back element seen in 危 danger and 急 urgent. Here it pictures someone stooping with a load on their back — exactly the original sense of 负 'to carry on the back, to shoulder.'
