https://www.rupeecase.com/blog/ Short notes on systematic investing, returns and risk maths, factors, portfolio construction, the cost of mutual funds and PMS, and behaviour. By Tanmay Kurtkoti. en-in Sat, 05 Sep 2026 08:00:00 +0530 https://www.rupeecase.com/blog/2026-09-05-morning-same-returns-different-retirement/ https://www.rupeecase.com/blog/2026-09-05-morning-same-returns-different-retirement/ Sat, 05 Sep 2026 08:00:00 +0530 The same ten annual returns leave a Rs 1 crore corpus drawing Rs 6 lakh a year at Rs 125.66 lakh or Rs 39.08 lakh depending only on their order. Returns and risk maths https://www.rupeecase.com/blog/2026-09-03-morning-three-ways-to-make-eighteen-percent/ https://www.rupeecase.com/blog/2026-09-03-morning-three-ways-to-make-eighteen-percent/ Thu, 03 Sep 2026 08:00:00 +0530 A brand, a retailer and a lender all show 18 percent ROE from 18x1x1, 3x3x2 and 20x0.09x10, and their returns on assets are 18, 9 and 1.8 percent. Company numbers https://www.rupeecase.com/blog/2026-09-02-morning-the-index-rewrites-itself/ https://www.rupeecase.com/blog/2026-09-02-morning-the-index-rewrites-itself/ Wed, 02 Sep 2026 08:00:00 +0530 The Nifty 50 made 41 constituent changes from 2009 to 2022, 2.93 a year, with a twenty rank buffer between joining and leaving and a cap of five additions a year. Costs: MF, PMS, RupeeCase https://www.rupeecase.com/blog/2026-09-01-evening-size-decides-more-than-selection/ https://www.rupeecase.com/blog/2026-09-01-evening-size-decides-more-than-selection/ Tue, 01 Sep 2026 08:00:00 +0530 Holding research constant and moving the top three weights from 5 to 20 percent each quadruples a 40 percent shock's damage from 6 to 24 percent of the book. Portfolio construction https://www.rupeecase.com/blog/2026-08-28-morning-the-stop-loss-that-did-not-stop/ https://www.rupeecase.com/blog/2026-08-28-morning-the-stop-loss-that-did-not-stop/ Fri, 28 Aug 2026 08:00:00 +0530 A stop is a trigger plus whatever fill exists, and in a 20 percent gap a 5 percent stop left 75 percent of the damage uncontrolled while circuit rules queued the exit. Behaviour https://www.rupeecase.com/blog/2026-08-26-evening-one-percent-is-not-one-percent/ https://www.rupeecase.com/blog/2026-08-26-evening-one-percent-is-not-one-percent/ Wed, 26 Aug 2026 08:00:00 +0530 On Rs 10 lakh at 12 percent gross for 25 years a 1.00 percent fee costs 20.1 percent of the ending corpus, and more than half of that is charged in the last five years. Costs: MF, PMS, RupeeCase https://www.rupeecase.com/blog/2026-08-25-evening-the-default-decides/ https://www.rupeecase.com/blog/2026-08-25-evening-the-default-decides/ Tue, 25 Aug 2026 08:00:00 +0530 Missing three instalments a year on a Rs 10,000 SIP cuts a twenty year corpus by 23.9 percent, and a skip in month one costs 9.7 times a skip in month 229. Behaviour https://www.rupeecase.com/blog/2026-08-24-morning-what-the-lock-in-costs-you/ https://www.rupeecase.com/blog/2026-08-24-morning-what-the-lock-in-costs-you/ Mon, 24 Aug 2026 08:00:00 +0530 Across ELSS, NPS and PPF the return argument is worth about Rs 54 lakh over twenty years and the NPS annuity clause moves Rs 40 lakh, decided by a paragraph nobody read. Personal finance and tax https://www.rupeecase.com/blog/2026-08-21-evening-the-average-return-is-a-lie/ https://www.rupeecase.com/blog/2026-08-21-evening-the-average-return-is-a-lie/ Fri, 21 Aug 2026 08:00:00 +0530 Plus 30, minus 20, plus 25, minus 15 averages 5.00 percent and compounds at 2.53, and a 12 percent average at 45 percent volatility compounds at 3.93. Returns and risk maths https://www.rupeecase.com/blog/2026-08-19-morning-the-edge-decays-when-you-read-about-it/ https://www.rupeecase.com/blog/2026-08-19-morning-the-edge-decays-when-you-read-about-it/ Wed, 19 Aug 2026 08:00:00 +0530 McLean and Pontiff measured 26 percent decay out of sample and 58 percent after publication, which stretches a 0.60 Sharpe's proof time from 11 years to 59. Factors https://www.rupeecase.com/blog/2026-08-19-evening-the-exemption-you-throw-away/ https://www.rupeecase.com/blog/2026-08-19-evening-the-exemption-you-throw-away/ Wed, 19 Aug 2026 08:00:00 +0530 Realising gains yearly in your own name beats deferring to exit up to about Rs 60 lakh of portfolio, because ten shots at the exemption are worth Rs 1,56,250 of tax. Costs: MF, PMS, RupeeCase https://www.rupeecase.com/blog/2026-08-17-evening-what-rebalancing-actually-pays/ https://www.rupeecase.com/blog/2026-08-17-evening-what-rebalancing-actually-pays/ Mon, 17 Aug 2026 08:00:00 +0530 Two 10 percent sleeves at 25 percent volatility earn a 1.88 point bonus at minus 0.20 correlation and 0.16 at plus 0.90, while a trending decade charges 1.39 points a year. Portfolio construction https://www.rupeecase.com/blog/2026-08-14-morning-selling-the-wrong-half/ https://www.rupeecase.com/blog/2026-08-14-morning-selling-the-wrong-half/ Fri, 14 Aug 2026 08:00:00 +0530 Twenty equal positions with winners sold at plus 20 and losers held to minus 40 end down 10 percent; flip the exit rule and the same picks end up 10, and doing nothing ends flat. Behaviour https://www.rupeecase.com/blog/2026-08-12-evening-profitable-and-broke/ https://www.rupeecase.com/blog/2026-08-12-evening-profitable-and-broke/ Wed, 12 Aug 2026 08:00:00 +0530 Stretching receivable days from 45 to 95 on 40 percent growth turns a 140 profit into minus 101 of operating cash, and the banker read the third statement first. Company numbers https://www.rupeecase.com/blog/2026-08-10-morning-prepay-or-invest/ https://www.rupeecase.com/blog/2026-08-10-morning-prepay-or-invest/ Mon, 10 Aug 2026 08:00:00 +0530 A Rs 5 lakh prepayment in month 12 of a Rs 50 lakh loan kills Rs 21.04 lakh of interest, and investing it still wins by about Rs 6 lakh at a post tax 9.36 percent. Personal finance and tax https://www.rupeecase.com/blog/2026-08-07-evening-twenty-funds-one-bet/ https://www.rupeecase.com/blog/2026-08-07-evening-twenty-funds-one-bet/ Fri, 07 Aug 2026 08:00:00 +0530 At the 0.85 correlation Indian diversified equity funds show against each other, twenty funds buy 1.17 effective bets against 1.14 for five. Portfolio construction https://www.rupeecase.com/blog/2026-08-06-morning-checking-too-often/ https://www.rupeecase.com/blog/2026-08-06-morning-checking-too-often/ Thu, 06 Aug 2026 08:00:00 +0530 At 12 percent drift and 18 percent volatility a day's wobble is 24 times the signal, a normal year shows about 121 red days, and the crossover sits at 2.25 years. Behaviour https://www.rupeecase.com/blog/2026-08-05-morning-momentum-pays-then-bites/ https://www.rupeecase.com/blog/2026-08-05-morning-momentum-pays-then-bites/ Wed, 05 Aug 2026 08:00:00 +0530 Momentum's winner minus loser portfolio runs a 0.71 Sharpe since 1927 and lost about 91 percent in two months of 1932 while the market rose 82, because the crash is the short leg. Factors https://www.rupeecase.com/blog/2026-08-03-morning-ten-days-that-mattered/ https://www.rupeecase.com/blog/2026-08-03-morning-ten-days-that-mattered/ Mon, 03 Aug 2026 08:00:00 +0530 Rs 10 lakh in the Nifty 50 TRI from July 1999 grew to Rs 2.84 crore, or Rs 96 lakh without the 15 best days, seven of which sat within two weeks of the ten worst. Behaviour https://www.rupeecase.com/blog/2026-08-03-evening-sort-by-return/ https://www.rupeecase.com/blog/2026-08-03-evening-sort-by-return/ Mon, 03 Aug 2026 08:00:00 +0530 Re sorting the shelf by Calmar moves Midcap Smallcap from rank two to eight and Large Mid Multi Asset from ten to four, because the recovery column is the one that matters. Strategy notes https://www.rupeecase.com/blog/2026-07-31-morning-stock-split-illusion/ https://www.rupeecase.com/blog/2026-07-31-morning-stock-split-illusion/ Fri, 31 Jul 2026 08:00:00 +0530 A 1:1 split turned 1,000 shares at Rs 200 into 2,000 at Rs 100, left the P/E and the ownership fraction untouched, and the volume bump faded within 90 days. Company numbers https://www.rupeecase.com/blog/2026-07-31-evening-volatility-tax/ https://www.rupeecase.com/blog/2026-07-31-evening-volatility-tax/ Fri, 31 Jul 2026 08:00:00 +0530 Five portfolios averaging 12 percent compound at 11.98 down to 4.00 percent depending only on volatility, so Rs 10 lakh over twenty years ends anywhere from Rs 96 lakh to Rs 22 lakh. Returns and risk maths https://www.rupeecase.com/blog/2026-07-30-morning-flat-sip-shrinks/ https://www.rupeecase.com/blog/2026-07-30-morning-flat-sip-shrinks/ Thu, 30 Jul 2026 08:00:00 +0530 Rs 10,000 a month buys about Rs 7,473 of 2021 purchasing power after five years at 6 percent inflation, and a 10 percent annual step up doubles the twenty year corpus. Personal finance and tax https://www.rupeecase.com/blog/2026-07-30-evening-confirmation-bias/ https://www.rupeecase.com/blog/2026-07-30-evening-confirmation-bias/ Thu, 30 Jul 2026 08:00:00 +0530 Lord, Ross and Lepper's 1979 study showed mixed evidence hardens both sides, and cutting at minus 15 instead of holding through minus 40 ends Rs 3.51 lakh ahead on Rs 10 lakh. Behaviour https://www.rupeecase.com/blog/2026-07-29-morning-three-year-number/ https://www.rupeecase.com/blog/2026-07-29-morning-three-year-number/ Wed, 29 Jul 2026 08:00:00 +0530 Every three year window on the Nifty 50 TRI from 2013 to 2025 ranged from 8.8 to 18.3 percent CAGR, and three months in 2020 moved it by 14 points. Returns and risk maths https://www.rupeecase.com/blog/2026-07-28-morning-dividend-yield-factor/ https://www.rupeecase.com/blog/2026-07-28-morning-dividend-yield-factor/ Tue, 28 Jul 2026 08:00:00 +0530 A 5 percent yield from a crashed price and one from a doubled payout look identical on a screener, and since April 2020 dividends are taxed at slab, 31.2 percent at the top. Factors https://www.rupeecase.com/blog/2026-07-28-evening-shallow-fall-compounds/ https://www.rupeecase.com/blog/2026-07-28-evening-shallow-fall-compounds/ Tue, 28 Jul 2026 08:00:00 +0530 Sorted by max drawdown instead of CAGR, Large Mid Multi Asset's 17.61 percent hole was the shallowest in the table and its 2025, up 10.1 percent, the best in the table. Strategy notes https://www.rupeecase.com/blog/2026-07-27-morning-sequence-of-returns/ https://www.rupeecase.com/blog/2026-07-27-morning-sequence-of-returns/ Mon, 27 Jul 2026 08:00:00 +0530 Reshuffling the same ten years leaves a lump sum unchanged, ends a retiree with 28 or 140 lakh, and makes an early crash a gift for someone still paying in. Returns and risk maths https://www.rupeecase.com/blog/2026-07-27-evening-disposition-effect/ https://www.rupeecase.com/blog/2026-07-27-evening-disposition-effect/ Mon, 27 Jul 2026 08:00:00 +0530 Odean found investors 1.5 times more likely to sell a winner than a loser, and the winners they sold beat the losers they kept by 3.4 points over the next year. Behaviour https://www.rupeecase.com/blog/2026-07-26-morning-buyback-illusion/ https://www.rupeecase.com/blog/2026-07-26-morning-buyback-illusion/ Sun, 26 Jul 2026 08:00:00 +0530 Retiring 15 percent of shares lifts EPS almost 18 percent on flat profit, and since October 2024 buyback proceeds are taxed as a deemed dividend at slab. Company numbers https://www.rupeecase.com/blog/2026-07-26-evening-tax-loss-harvest/ https://www.rupeecase.com/blog/2026-07-26-evening-tax-loss-harvest/ Sun, 26 Jul 2026 08:00:00 +0530 Booking a Rs 60,000 short term loss against a Rs 1 lakh short term gain cuts the tax from Rs 20,000 to Rs 8,000, and unused losses carry eight years if you file on time. Personal finance and tax https://www.rupeecase.com/blog/2026-07-24-morning-low-vol-anomaly/ https://www.rupeecase.com/blog/2026-07-24-morning-low-vol-anomaly/ Fri, 24 Jul 2026 08:00:00 +0530 A dollar in the calmest US stocks grew to about 70 from 1968 to 2011 against under 8 in the wildest, and the Nifty 100 Low Volatility 30 did 17.5 against 13.7 percent over 2005 to 2020. Factors https://www.rupeecase.com/blog/2026-07-24-evening-mix-beats-the-pick/ https://www.rupeecase.com/blog/2026-07-24-evening-mix-beats-the-pick/ Fri, 24 Jul 2026 08:00:00 +0530 Brinson's 90 percent is about variability over time, not return; the same index at 100/0/0 and 40/40/20 trades 2.2 points of return for a worst drop of 28 instead of 52. Portfolio construction https://www.rupeecase.com/blog/2026-07-23-morning-sector-fund-concentration/ https://www.rupeecase.com/blog/2026-07-23-morning-sector-fund-concentration/ Thu, 23 Jul 2026 08:00:00 +0530 Financial services is 37.7 percent of the Nifty 50, so a sector fund that must hold 80 percent financials pushes a 30 percent sleeve past half the book in one sector. Costs: MF, PMS, RupeeCase https://www.rupeecase.com/blog/2026-07-23-evening-lump-sum-vs-drip/ https://www.rupeecase.com/blog/2026-07-23-evening-lump-sum-vs-drip/ Thu, 23 Jul 2026 08:00:00 +0530 Vanguard's 1926 to 2022 data across seven markets shows a lump sum beat a three month drip about two times in three, and stretching the drip lowers the odds. Personal finance and tax https://www.rupeecase.com/blog/2026-07-22-evening-nominee-is-not-an-heir/ https://www.rupeecase.com/blog/2026-07-22-evening-nominee-is-not-an-heir/ Wed, 22 Jul 2026 08:00:00 +0530 The Supreme Court held in 1983 and 2023 that a nominee only receives; without a will, Rs 80 lakh to a sole nominee wife is owned one quarter each by four Class I heirs. Personal finance and tax https://www.rupeecase.com/blog/2026-07-21-morning-size-factor/ https://www.rupeecase.com/blog/2026-07-21-morning-size-factor/ Tue, 21 Jul 2026 08:00:00 +0530 Midcap, Smallcap and Microcap printed 41.21, 41.03 and 40.56 percent while the Allcap basket did 48.02 with a similar worst drop, so small on its own is not an edge. Factors https://www.rupeecase.com/blog/2026-07-21-morning-overlap-cap/ https://www.rupeecase.com/blog/2026-07-21-morning-overlap-cap/ Tue, 21 Jul 2026 08:00:00 +0530 SEBI's February rule treats two schemes as duplicates above 50 percent overlap but carves out large caps, which is exactly where two plain funds share 60 to 80 percent. Costs: MF, PMS, RupeeCase https://www.rupeecase.com/blog/2026-07-21-evening-who-sells-first/ https://www.rupeecase.com/blog/2026-07-21-evening-who-sells-first/ Tue, 21 Jul 2026 08:00:00 +0530 A shared portfolio is held by consensus and sold by veto, so the account's risk level is the lower partner's tolerance, not the average. Portfolio construction https://www.rupeecase.com/blog/2026-07-20-morning-turnover-tax/ https://www.rupeecase.com/blog/2026-07-20-morning-turnover-tax/ Mon, 20 Jul 2026 08:00:00 +0530 A 5.7 percent gross premium became 4.2 after trading costs, and factors traded slower than about half the book a month tend to keep a net edge. Factors https://www.rupeecase.com/blog/2026-07-20-evening-midcap-drawdown/ https://www.rupeecase.com/blog/2026-07-20-evening-midcap-drawdown/ Mon, 20 Jul 2026 08:00:00 +0530 The Midcap card spent 322 days below its high and fell almost 24 percent in two months of 2025, and the 41 percent CAGR belonged to whoever stayed seated. Strategy notes https://www.rupeecase.com/blog/2026-07-19-morning-since-inception-trap/ https://www.rupeecase.com/blog/2026-07-19-morning-since-inception-trap/ Sun, 19 Jul 2026 08:00:00 +0530 A six year old fund's 18.9 percent since inception rode a 75 percent birth year; on the same five years it did 10 against the fifteen year old fund's 13. Returns and risk maths https://www.rupeecase.com/blog/2026-07-19-evening-two-sets-of-books/ https://www.rupeecase.com/blog/2026-07-19-evening-two-sets-of-books/ Sun, 19 Jul 2026 08:00:00 +0530 A parent's standalone profit of Rs 45 crore, consolidated Rs 140 crore and attributable Rs 100 crore give P/Es of 33, 11 and 15 on the same market value. Company numbers https://www.rupeecase.com/blog/2026-07-18-morning-one-country-bet/ https://www.rupeecase.com/blog/2026-07-18-morning-one-country-bet/ Sat, 18 Jul 2026 08:00:00 +0530 Japan was 45 percent of world equity in 1989 and took 34 years to regain its high; India is about 2.9 percent and most Indian portfolios sit near 100 percent India. Portfolio construction https://www.rupeecase.com/blog/2026-07-18-morning-home-bias/ https://www.rupeecase.com/blog/2026-07-18-morning-home-bias/ Sat, 18 Jul 2026 08:00:00 +0530 54 of 66 international funds were closed to fresh money under a 7 billion dollar industry cap set in 2008, so one country concentration is often found rather than chosen. Portfolio construction https://www.rupeecase.com/blog/2026-07-18-evening-tax-free-allowance/ https://www.rupeecase.com/blog/2026-07-18-evening-tax-free-allowance/ Sat, 18 Jul 2026 08:00:00 +0530 Booking about Rs 1.25 lakh of long term gains each year and rebuying cuts the exit tax on a Rs 96 lakh corpus from Rs 10.65 lakh to Rs 7.68 lakh. Personal finance and tax https://www.rupeecase.com/blog/2026-07-17-morning-funds-that-vanished/ https://www.rupeecase.com/blog/2026-07-17-morning-funds-that-vanished/ Fri, 17 Jul 2026 08:00:00 +0530 About one in four Indian large cap funds disappeared over ten years, and the category average you see is the average of the survivors. Costs: MF, PMS, RupeeCase https://www.rupeecase.com/blog/2026-07-17-evening-worst-so-far/ https://www.rupeecase.com/blog/2026-07-17-evening-worst-so-far/ Fri, 17 Jul 2026 08:00:00 +0530 The Nifty's worst fall inside the backtest window is 16.92 percent, against about 38 percent in 2020 and 60 percent in 2008, so double the worst number you see. Strategy notes https://www.rupeecase.com/blog/2026-07-17-evening-bonus-shares/ https://www.rupeecase.com/blog/2026-07-17-evening-bonus-shares/ Fri, 17 Jul 2026 08:00:00 +0530 A 1:1 bonus doubled the share count and halved the price, left Rs 80,000 worth Rs 80,000, and started a fresh holding period clock on the new shares. Company numbers https://www.rupeecase.com/blog/2026-07-16-morning-goodwill-overpaid/ https://www.rupeecase.com/blog/2026-07-16-morning-goodwill-overpaid/ Thu, 16 Jul 2026 08:00:00 +0530 A Rs 400 crore goodwill write down can turn a 500 crore profit year into 100 without a rupee of cash moving, as Tata Steel's Corus impairment showed. Company numbers