1/ What Happens with More Funds than Stocks? (Madhavan, Sobczyk, Ang)

"Funds differ meaningfully in terms of individual stock holdings, and we examine the factor exposures of the typical fund and the cross section of holdings of different funds."

https://t.co/d6vU4Fgszg

2/ * Data on fund holdings are from Morningstar
* Sample: Jan. 1, 2007 to Dec. 31, 2018
* Only funds with at least 80% of holdings from the Russell 3000 universe are considered
* Mean AUM-weighted expense ratio for mutual funds (ETFs) is 70 bps (14.2 bps) as of Q4 2018
3/ "The holdings of ETFs and active mutual funds across U.S. stocks can be efficiently summarized by approximately 10 canonical funds.

"There is more commonality explained by the first few canonical funds for active mutual funds than for ETFs."
4/ "Commonality among equity mutual funds has remained approximately constant, but there has been increased dispersion in ETF offerings.

"We see no apparent rise in concentration or crowding for mutual funds over the period from January 2007 to December 2018."
5/ "We examine commonality in active mutual funds in Morningstar style box categories. While Value and Blend commonality has remained roughly constant over the period 2007-2018, Growth funds have exhibited a marked increase in crowded positions."
6/ "Crowding is greater in factors than in individual stocks for both active mutual funds and ETFs. Factor crowding has remained relatively constant over the period examined."
7/ "The first archetypal “fund” that approximates the whole active fund universe is a market-cap index.

"The second most important is value-growth exposure.

"For ETFs, unlike active funds, the second degree of differentiation reflects both value-growth and sector exposures."
8/ "Overall, the first approximation of the stocks held by funds is that the stocks tend to be large growth stocks. In an additional second approximation, funds tend to hold stocks that are smaller with higher volatilities."
9/ "Price discovery of underlying stocks in the S&P 500 can occur through ETFs or through trades of the stocks themselves—but this has only been the case since 2015. Before then, there were fewer listed ETFs that held S&P 500 stocks compared to number of stocks in index itself."

More from Trading

Many of you have seen the famous Westrum Organizational Typology model, so prominently featured in State of DevOps Research, Accelerate, DevOps Handbook, etc.

This model was created Dr. Ron Westrum, a widely-cited sociologist who studied the impact of culture on safety


Thanks to Dr. @nicolefv, I was able to interview him for an upcoming episode of the Idealcast! 🤯

It was a very heady experience, and while preparing to interview him, I was startled to discover how much work he's done in healthcare, aviation, spaceflight, but also innovation.

I've read 4+ of his papers, so I thought I was familiar with his work. (Here's one paper:
https://t.co/7X00O67VgS)

I was startled to learn he has also studied in depth what enables innovation. He wrote a wonderful book "Sidewinder: Creative Missile Development at China Lake"


Dr. Westrum writes about China Lake Research Labs: "its design and structure had one purpose: to foster technical creativity. It did; China Lake operated far outside the normal envelope... Sidewinder & others were "impossible" accomplishments,

I love this book because it describes traits of organizations that routinely create and maintain greatness: US space program (Mercury, Gemini, Apollo), US Naval Reactors, Toyota, Team of Teams, Tesla, the tech giants (Amazon, Google, Netflix, Google)

You May Also Like

A brief analysis and comparison of the CSS for Twitter's PWA vs Twitter's legacy desktop website. The difference is dramatic and I'll touch on some reasons why.

Legacy site *downloads* ~630 KB CSS per theme and writing direction.

6,769 rules
9,252 selectors
16.7k declarations
3,370 unique declarations
44 media queries
36 unique colors
50 unique background colors
46 unique font sizes
39 unique z-indices

https://t.co/qyl4Bt1i5x


PWA *incrementally generates* ~30 KB CSS that handles all themes and writing directions.

735 rules
740 selectors
757 declarations
730 unique declarations
0 media queries
11 unique colors
32 unique background colors
15 unique font sizes
7 unique z-indices

https://t.co/w7oNG5KUkJ


The legacy site's CSS is what happens when hundreds of people directly write CSS over many years. Specificity wars, redundancy, a house of cards that can't be fixed. The result is extremely inefficient and error-prone styling that punishes users and developers.

The PWA's CSS is generated on-demand by a JS framework that manages styles and outputs "atomic CSS". The framework can enforce strict constraints and perform optimisations, which is why the CSS is so much smaller and safer. Style conflicts and unbounded CSS growth are avoided.