Hi I am trying to make to make a strategy where I will get a bucket of Top 50 (or some other number) stocks as per dollar volume through pipeline.

Now, I will compute their respective Beta's (wrt. SPY maybe?) and then compute weights in-order to minimise the overall Beta.

I've recently started working with Quantopian and I am really struggling with implementing few basics, I would really appreciate some help.

Things where I'm stuck:

1. How do I get Beta's of respective stocks? I was trying to implement it by using 'RollingLinearRegressionOfReturns' in make_pipeline() and I couldn't figure out what target should be given to RollingLinearRegressionOfReturns.

   1. Can you give me few leads on how to compute weights such that it minimises the overall portfolio beta?

Attaching my code here

from quantopian.algorithm import attach_pipeline, pipeline_output  
from quantopian.pipeline import Pipeline  
from quantopian.pipeline.data.builtin import USEquityPricing  
from quantopian.pipeline.factors import AverageDollarVolume,RollingLinearRegressionOfReturns  
from quantopian.pipeline.filters.morningstar import Q500US  
from quantopian.pipeline.filters import Filter  
def initialize(context):  
    schedule_function(allot, date_rules.week_start(), time_rules.market_open(minutes=30))  
    attach_pipeline(make_pipeline(), 'my_pipeline')  


def make_pipeline():  
    dollar_volume = AverageDollarVolume(window_length=5)  
    top_dollar_volume = dollar_volume.top(50)  
    pipe = Pipeline(  
        screen = top_dollar_volume,  
    )  
    return pipe  


def before_trading_start(context, data):  
    context.output = pipeline_output('my_pipeline')  
    context.security_list = context.output.index.tolist()  
    context.beta_list = []  
    for se in context.security_list:  
        reg = RollingLinearRegressionOfReturns(  
        target=se,  
        returns_length=2,  
        regression_length=30,  
    )  
        context.beta_list.append(reg.beta)  
    print context.beta_list #This is not printing the Beta value  

def allot(context,data):  
    pass  

Thanks