In the academic paper Industries and Stock Return Reversals by Hameed and Mian (JFQA,2015) (see picture below), the authors describe a trading strategy based on reversal, which essentially buys past losers and sell past winners.
I do not fully understand how they come up with those portfolio weights. I understand the idea of the 50% margins, but what is not clear to me is how the weights can actually be considered weights as they do not necessarily add up to 1. Take as an example two assets, A and B, with returns $R_a=0.3$ and $R_b = -0.2$. Assume $R_m=0$ for simplicity. Following their rule, the weight for A will be -(0.3)/0.25 = -1.2 and for B +(0.2/1.2)=0.8 because H=0.5*(abs(0.3)+abs(0.2))=0.25. The two weights sum up to -0.4. So how can I actually invest in this? Even if we forget about the 1/2 scaling in H, the weights would still add up to -0.2. How would you actually calculate the weights in practice in this situation?