Following up on our live chat, the problem is that positions that are already held are not rebalanced to reflect the equal weighting that your algo is trying to achieve. For example, say in one bar you order 10 securities with value equal to 10% of your portfolio value each. In the next bar, say you are interested in ordering 10 new securities, the orders variable will equal 20 (10 existing positions + 10 new positions), so you should be ordering up to 5% portfolio value in each of the 10 new securities. Since the previously held positions are not rebalanced down to 5% as well, you are now holding: (10 * 10%) + (10 * 5%) = 150% of your portfolio value. To get around this, you will need to rebalance the positions that you already hold as well.
I hope this helps!
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