Fellow brokers, can you please give me your opinion on this wording? It's a matter of over $10,000 a month depending on how you read it.
In question is the base rent due for an option period:

"Base Rent payable during each Option Period shall be an amount determined on the first day of such Option period by multiplying the Base Rent payable during the first year of the Initial Lease Term by an amount equal to eighty percent (80%) of the percentage increase, if any, in the index defined...”

To save some time with the index wording, the increase in CPI from the original term to now is 106.6. Original CPI 150.5, CPI now 257.1. 

I don't want my opinion to play a factor in any answers so I will not state what I believe to be correct. Would love to discuss before we get an attorney involved. 

Thanks for your help.

EDIT: I was 4 years old when this lease was finalized. So clearly I wasn't involved in any discussion about this.
[{"id": "d34ab9k", "text": "Four years old?   on that timescale, how come people lease rather than buy?  I know people do it, so there must be a reason.  \n\nAlso, if there is more than $120K/yr on or off the table based on a change in wording, it seems like it would make a lot of sense to talk with an hourly lawyer, at least.  Maybe not bringing said lawyer into the negotiation directly, but at least consult in private.    ", "replies": [{"id": "d34bf6o", "text": "In this case this is a tenant in a shopping center, landlord not willing to sell just a piece of the center.\n\nBut yes it's definitely something that is going to need a lawyer in the end. Just trying to get a better understanding for myself. thanks!", "replies": [], "depth": 2}, {"id": "d35587o", "text": "Less risk. Less capital required. In a shopping center, other tenants help drive traffic. ", "replies": [{"id": "d35k5rg", "text": "&gt;Less risk.\n\nHuh.  'cause last time I went for a commercial lease, they wanted a personal co-sign, making me personally responsible for paying the rent for the term of the lease.   on a 5 year lease, the potential liability there is dramatically more than the 6% commission to sell the place.\n\nOf course, if you are expecting a huge downturn in the real-estate market, then yes, there is potentially more risk.    In my experience, though, there seems to be a dramatically larger chance of your business venture going under than there is of a 2008 style real-estate crash, so buying seemed lower risk to me, though yeah, the up-front capital requirements can sometimes force you into that less desirable \"fine, if the business goes under, I'm bankrupt\" situation.   It's just an ugly place to be.\n\n\n&gt;In a shopping center, other tenants help drive traffic. \n\nYea, but that isn't really relevant to the 'lease vs buy' discussion, because there are shopping centers that are owned condo-style, too.    Maybe the shopping center you want to be in is only available as a lease... but that would be an indicator that leasing is generally a less good deal for the tenant, one you'd only take if you were getting other benefits (like a really sweet location) that you are willing to pay extra for. \n\n", "replies": [{"id": "d35pu3c", "text": "In general, if you're an owner, good luck collecting on every personal guaranty. You'd rather strike a payoff or lower rent before litigating. \n\nTo be a real estate owner you have to buy it all cash or finance it. If you buy all cash, all of that money is at risk and there is objectively more capital markets risk unless you naively assume you can exit at the exact same cap rate you bought it. With financing you're adding 4-6% to your occupancy cost so cutting into margins which may already be slim. You might get a lower rate and higher LTV if you sign up for a recourse loan. \n\nFor any given piece of real estate, your list of qualified buyers is shorter than your list of qualified tenants. \n\nThen again, if you operate every location corporately and have 100+ locations, it can make sense to own because your cost of capital is lower.", "replies": [{"id": "d35qw66", "text": "&gt;In general, if you're an owner, good luck collecting on every personal guaranty. You'd rather strike a payoff or lower rent before litigating. \n\nSure, but they're not going to settle for less than they can get... e.g. if you are not near bankrupt already, the best you can reasonably hope for is to get them to discount it by whatever they'd have to pay the lawyers to make you pay the full amount, otherwise they are just leaving money on the table.  \n\n(Of course, if you *are* near bankrupt already, you have a lot more leverage, and yes, in that case, it makes sense for the landlord to take something; anything, really, rather than risk fighting your other creditors for what remains.)  \n\n", "replies": [], "depth": 5}], "depth": 4}], "depth": 3}], "depth": 2}], "depth": 1}, {"id": "d34ajc5", "text": "jfc...they should put this shit on the SATs.\n\nMy best guess is that 106.6 is the amount of the increase, which is 71% greater than the original CPI index so that should be the percentage increase that you apply the 80% meaning a 57% increase of the original base rent. I can see how you would end up with 47% as well, but I think that's ignoring **percentage** increase. Definitely consult an attorney.", "replies": [{"id": "d34bj7i", "text": "right... it's so unclear. Something like this needs an example to make sure both sides understand when the lease expires 20+ years later. Thanks for your input I appreciate it.", "replies": [{"id": "d34ej69", "text": "At least I had fun kind of working it out haha. Post an update if you remember to when it's sorted out!", "replies": [], "depth": 3}, {"id": "d34hmju", "text": "It's clear as gold, look up in any mathematics textbook and you will find how percentage increase is defined....I have my BSME and minor in math and this is just about the only time it's useful haha.", "replies": [], "depth": 3}], "depth": 2}], "depth": 1}, {"id": "d34f049", "text": "So (106.6/150.5 = 70.8%) * 80% = 56.6%  \n\nOr (150.5/257.1 = 58.5%) * 80% = 46.8%  \n\nI think the wording for CPI is key to decipher whether or not you mean the raw change in the index, or if it's the actual percentage change. Are there any other defined terms in there that you need to check definitions for? ", "replies": [], "depth": 1}, {"id": "d34fbih", "text": "Should be paying on 235.78, or 70.8....all your lawyer will do is look up how it is defined. Which is below.\n\nPercent Increase = (Final Value ( 257.1) - Initial Value ( 150.5) )/ Initial Value ( 150.5)  * 100%\n\nSo it will be 70.8% * the %80 = 56.6% even if it goes to court.", "replies": [], "depth": 1}, {"id": "d34pww3", "text": "What kind of property is it? I've never seen (retail leasing) option rent langue that deep in the weeds. ", "replies": [], "depth": 1}, {"id": "d351j1k", "text": "I'm really tired, but it seems like part of your equation is missing.\n\nDefinition: \n\nCurrent CPI 257.1\n\n(The current) Base Rent payable shall be an amount determined \n\nby multiplying \n\nthe (initial) base Rent 150.5\n\nby eighty percent of the percentage increase 106.6/150.5 (70.8%)\n\n70.8 percentage increase X .80 = 56.64... \n\n\u2026that\u2019s where the instructions end.\n\nBut the semantics are saying to multiply base rent 150.5 X 80% of percentage increase, so when we do that we get (150.5 X 56.65 = 8,524.32). I don't know what the units are.\n\nWhat's missing?\n", "replies": [], "depth": 1}, {"id": "d35brtj", "text": "If we accept that 80% of the percentage increase is 56.65%, as others have been saying more or less, the exact wording is to multiply by \"an amount equal to eighty percent (80%) of the percentage increase\"\n\nSo technically it would be 56.65% of the initial base rent. **However**, (I am not a lawyer), in cases like these past actions and the obvious intention of the contract will hold in court, and the rent should probably be 156.65% of the initial base rent, and that should probably hold up in court.", "replies": [{"id": "d37m785", "text": "So this is what I find to be the correct amount also, multiplying the base rent payable during the 1st year of the term by 156.65%. This is the only way to get a rent number that makes any sense. The problem I'm having is explaining why this is correct way of looking at this. Any ideas would be MUCH appreciated if you have the time. ", "replies": [{"id": "d37o51y", "text": "You need a lawyer. \n\nThe reason is because no landlord in their right mind would knowingly write a contract for less rent every year, and if the tenant has been there for so long, they know this and are perhaps trying to get off on a technicality. However, they would have had to sue in the first year or couple of years, not 20-40 years later. Depending on your jurisdiction this is much less of a big deal than it may seem at first. \n\nCommon sense does come into play in the enforcement of contracts like this, and although I can't pull up something off the tip of my tongue, there have certainly been many, many judgments that favor the common sense reading contrary to the technical language employed in RE contracts. This would be a brutal mistake if caught in year one, because the tenant could claim they signed with that understanding, but that ship sailed decades ago.", "replies": [], "depth": 3}], "depth": 2}], "depth": 1}, {"id": "d4crcua", "text": "So was this resolved? Who won? :)", "replies": [{"id": "d4d7cwf", "text": "I wish! Attorneys are currently reviewing the language. The lease says we can't utilize arbitration for anything over $50,000. This equates to a few million. After studying up a lot I can honestly say both sides have an argument, so I don't think this will end anytime too soon. I'll make sure to add some updates!", "replies": [{"id": "d4d7lhw", "text": "See if you can tag my username in the update. I'd love to see how this turns out :)", "replies": [{"id": "d4dd0cn", "text": "I definitely will!", "replies": [], "depth": 4}], "depth": 3}], "depth": 2}], "depth": 1}]